#RPG Rulings – Understanding Gravity in #TheExpanse Using #CepheusEngine #TravellerRPG

Season 5 of The Expanse TV series is streaming now, which means its that time of the TV season that I look once again at how I can take the hard-ish science fiction of James S.A. Corey and depict it in a roleplaying game campaign. This time I am focused on one foundational aspect of the setting that I took for granted before – gravity.

Getting Down with Gravity in The Expanse

Gravity in The Expanse is kept fairly realistic. The sources of gravity are what we expect from our current understanding of physics. Gravity is created by mass (planets, moons, planetoids, asteroids), spin habitats, or along the thrust vector of ships. Gravity is also a vital part of the cultures in The Expanse. From Belters who are tall and lanky from growing up in low-g but weak in normal gravity to Martian Marines who train at 1-g to be ready to fight on Earth, gravity is an important descriptor (discriminator?) between different factions. Gravity also has important impacts to space travel and combat; look no further than the need for “the juice” to withstand high-g acceleration or maneuvers or how it acts to limit human activities if one’s body is subjected to high-g stress for long durations (not to mention the catastrophic consequences of decelerating too quickly, yuck).

Courtesy pintrest.com

Rules of Gravity

I don’t presently own The Expanse Roleplaying Game from Green Ronin so I do not know the details of how they handle gravity in that setting. However, I am a long-time Traveller RPG player. These days I enjoy the modern incarnation of the Original 2d6 Science Fiction Roleplaying Game by using the Cepheus Engine rules set.

For my exploration of of gravity and The Expanse, I focused on five RPG rule sets or settings:

I really appreciate how all these various rule sets can work together to create an internally consistent, plausible setting. Although I use all these different rules sets and settings for reference, I will describe my rules interpretations primarily in Cepheus Engine terms for ease of integration across the various rules incarnations. My goal here is not to “science the sh*t” out of gravity in my RPG campaign, but to lean on a reasonable set of rules to provide good setting “flavor.”

Characters and Gravity

Characters in Cepheus Engine are described using three physical characteristics; Strength, Dexterity, and Endurance. The usual character generation method is to roll 2d6 for each characteristic. Each characteristic can range from 1 to 15 with 7 being a human average. Interestingly, when creating the physical characteristics of a character, there is no adjustment in the rules based on a low-gravity homeworld. Instead, an (assumed) low gravity homeworld grants certain default skills. Specifically, a homeworld with a Trade Code of “Asteroid” or “Vacuum” earn the Zero-G-0 skill (CESRD, p. 26)

The CESRD also has rules for alien species that are not specifically intended for human characters but I note them here as they may prove useful:

  • Notable (Characteristic): Some species are notably dexterous, intelligent, tough or strong. Characters from such races have a positive Dice Modifier when rolling for that characteristic (+2 unless otherwise specified), and their racial maximum for that characteristic is increased by the same amount. (CESRD, p. 44)
  • Weak (Characteristic): The opposite of Notable (Characteristic), some species are weaker, less resilient or less well educated than others. Characters from such races have a negative Dice Modifier when rolling for that characteristic (-2 unless otherwise specified), and their racial maximum for that characteristic is decreased by the same amount. (CESRD, p. 45)

The Clement Sector setting supplement Tree of Life: Altrants in Clement Sector defines an altrant as, “groups of humans which, from birth, have been altered thanks to advanced genetic manipulation, to have abilities different than a baseline human. These changes were most often made to allow humans to be able to perform tasks and live in environments which would be difficult or impossible for baseline humans.” If one ignores the “genetic manipulation” and instead views the change as “naturally evolved” then two Body Alterations found in this supplement may be useful:

  • Muscle Increase Package: Often referred to as the “Hercules” alteration, this procedure alters the body to make it as strong as it can possibly be. This alteration is the equivalent of years of strength training and will give the body the appearance of a successful bodybuilder. Taking this alteration gives the character +3 to their STR and -3 to their DEX immediately after the full alteration time period has passed. (Tree of Life, p. 45)
  • Vestibular System (Improved): This alteration improves the sensory system which provides the user with their sense of balance, spacial orientation, and balance. This gives the character a +2 DM to any physical task performed in gravity of less than 0.50 standard. However, the character will suffer a -2 DM to any physical task attempted in gravity of more than 1.25 standard (Tree of Life, p. 49)
Courtesy geekwire.com

The CESRD is also limited in what affect gravity has on characters. The skill “Zero-G” provides some guidance for actions in zero-gravity environments:

Zero G: The Character is acclimated to working and living in micro-gravity environments and freefall. The character is trained and familiar with the use of weapons and combat in such environments. In addition, the individual has been trained in the wearing, care, and maintenance of all types of Vacuum Suits and Combat Armor commonly used in these conditions.

CESRD, p. 57

[As an aside, looking back over the history of Traveller, the Zero-G skill, seemingly so foundational to a science fiction setting, has evolved in interesting ways. In Classic Traveller Little Black Book 1: Characters and Combat, one finds the skill Vacc Suit but not Zero-G. The CESRD has Zero-G but not Vacc Suit. T5 has both Vacc Suit (which it names as a Default Skill that all characters start with) AND Zero-G.]

Rules for “High and Low Gravity Worlds” are found in Chapter 12: Worlds of the CESRD:

High and Low Gravity Worlds: Worlds where the gravity is 0.75 or less are low-gravity worlds….Humans tend to find life on low-gravity worlds to be initially pleasant, but regular exercise regimes and medicinal supplements are required to prevent bone and muscle degradation. Those who spent too long on low-gravity worlds cannot tolerate higher gravities. Characters on low-gravity worlds suffer a -1 DM to all skill checks until they acclimatize, a process which takes 1D6 weeks. Characters with Zero-G skill at level 0 or better acclimatize instantly.

High-gravity worlds have a gravity 1.25 times or more than of Earth….Humans find high-gravity worlds unpleasant. Especially high-gravity worlds require the use of pressured or powered suits to support the human frame. Characters on high-gravity worlds suffer a -1 DM to all skill checks until they acclimatize, a process that takes 1D6 weeks.

CESRD, p. 168

Going back deep into the Classic Traveller lore, Module 2: Beltstrike includes rules for activities in zero and low gravity. Basically put, anytime the characters attempted to move or otherwise act in zero-g they had to make a saving throw of 10+ (on 2d6), applying modifiers as found on the Zero-G Activities Chart:

Classic Traveller Module 2: Beltstrike, p. 11

The more recent Orbital 2100 also provides rules for activities in zero-g environment. The task roll in Orbital 2100 is the spiritual successor of Beltstrike but greatly simplified:

Every crewman on DSV [Deep Space Vehicle] or orbital vehicle will have Zero-G skill-0 as standard. Higher levels of the skill are indicative of much greater experience of working in zero gravity. A crucial task, whether it is aligning and antenna or an EVA, shooting someone with a revolver or trying to shut an airlock door quickly to prevent an intruder forcing their way in, requires a skill check. For regular activities, skip the rolls entirely.

Avoid Losing Control in Zero-Gravity: Zero-G, Dexterity, Instant, Average (+0)

Apply the following DMs: Using a tool to repair/construct -2, Firing a gun -3, striking with tool, weapon, fist etc., or pushing/pulling -4, using a handhold +2

Losing control means that the task has failed until control reestablished, the character is tumbling! Roll again to regain control, but this time there are no DM’s, either positive or negative, except for those derived from Zero-G skill and Dexterity characteristic.

Orbital 2100 v3, p. 125

Before we get into making a character for The Expanse, let’s also consider what the spacecraft in book and TV series show us.

Ships and Gravity

The Expanse Canon

Way back in October 2016 and February 2017 I did two posts on how I viewed the depiction of spacecraft in The Expanse in Cepheus Engine-terms. To recap, there are three basic forms of Maneuvering Drive (M-Drive) shown in The Expanse; the “Teakettle,” the fusion torch, and the Epstein Drive:

Flying teakettle was naval slang for flying on the maneuvering thrusters that used superheated steam for reaction mass. The Knight‘s fusion torch would be dangerous to use this close to the Canterbury and wasteful on such a short trip. Torches were pre-Epstein fusion drives and far less efficient.

Leviathan Wakes, Chapter 3

By doing some backwards math I worked out that the “Teakettle” tops out at 2-G acceleration. Based on the upper limits of the instruments in Solomon Epstein’s ship, the fusion torch appears to have a limit of 7-G acceleration. In the novella The Drive, Epstein’s new drive pushes him at something like 12-Gs and in Season One of The Expanse the Rochinante pushes upwards of 17-G acceleration. As fast and exciting a high-speed run is, the mundane reality of travel in The Expanse is that ships usually plod along at a much slower cruising rate. Judging from the book Leviathan Wakes and the novella The Drive it appears that “cruising speed” is somewhere around 0.3-G acceleration. This ‘minimal acceleration provides just enough g-force to avoid the penalties of zero-g activities. This low-G acceleration is also important to note because it plays into the design of the ships.

Courtesy Syfy.com

Ship Gravity Using Cepheus Engine

One of the major “handwavium” technologies in Classic Traveller and now Cepheus Engine is that with the advent of the gravity-based maneuver drives you also get artificial gravity, known in the Traveller setting as “Compensators”:

  • Compensators. Integral to Maneuver Drives, Gravitic Drives, and Lifters is an inertial compensation component which counteracts the effects on acceleration on occupants of the ship. (T5 v5.10, Book 2: Starships, “How Maneuver Works,” p. 101)

In The Expanse there is no artificial gravity device for spacecraft so we need to find some rules to help us depict what happens with too much, or too little, gravity and what design decisions can be made to compensate.

Gel-y Juice

In The Expanse, there are two technologies for dealing with the crushing force of high-g acceleration. The first is acceleration gel; “Thirty minutes later, the engines kicked on, pressing him into the acceleration gel at a joint-crushing high-g burn for thirteen days, with one-g breaks for biological function every four hours.” (Leviathan Wakes, Chapter 46)

The second acceleration compensating technology is “The Juice:”

Going on the juice was pilot-speak for a high-g burn that would knock an unmedicated human unconscious. The juice was a cocktail of drugs the pilot’s chair would inject into him to keep him conscious, alert, and hopefully stroke-free when his body weighed five hundred kilos. Holden had used the juice on multiple occasions in the navy, and coming down afterward was unpleasant. 

Leviathan Wakes, Chapter 5

Standing Up In Space

The design of ships in The Expanse is also driven by the lack of an artificial gravity device. Fortunately, the setting of Orbital 2100 is in our near future and leans heavily into pre-gravitic spacecraft design similar to The Expanse and therefore can be used as a guide:

The biggest difference in space technology is the absence of anti-gravity….Not only are the drives different but the lack of on-board gravity means the crew must operate in zero-G throughout the mission. The only way to mitigate this is the installation of spin habitats, or rotating sections of the spacecraft, that ‘simulate’ gravity.

Orbital 2100, Chapter 5: Spacecraft Design, p. 37

For The Clement Sector setting, ship design is found in the Anderson & Felix Guide to Naval Architecture. Included in A&F is a module for designing Pre-Gravitic Drive Spacecraft. Here we actually get rules for continuous micro-gravity exposure as well as alternate methods of producing artificial gravity, both of which are also featured in The Expanse:

For every four week period of continuous micro gravity exposure there will be a one point strength and endurance characteristic loss that will require 1d6 weeks of recover in a one standard gravity environment.

The two main methods of producing artificial gravity are:


Producing “rear is down” gravity

A ship under acceleration will produce thrust gravity. In this instance the ship’s internal layout will need to be perpendicular to the axis of the ship or ninety degrees to the line of flight.

Centrifugal Rotation

Producing “out is down” gravity

For any type of method using centrifugal rotation to produce gravity, the internal layout must be aligned so that decks face inward towards the center of the rotation arc.

Anderson & Felix Guide to Naval Architecture, “Artificial Gravity,” p. 106
Courtesy syfy.com

Expanse-ive Characters

Having looked at many rules of Traveller and Cepheus Engine, how do I think characters from The Expanse could be portrayed?

Building a Better Belter

For Belter characters, at character generation I give each the Weak (Strength) and Weak (Endurance) trait from the CESRD alien species listing. I also give Belters the Vestibular System (Improved) alteration found in The Clement Sector supplement Tree of Life. Note that Belters grow up with the Zero-G skill so they instantly acclimatize when moving between different gravity world unless they cannot exercise or medicinal supplements are not available. To simulate the absence of such I ruled that they suffer loss of strength and endurance the same as if they were exposed to micro gravity for long periods.

I’ll point out here that the Belter career in the CESRD is perfectly adequate for generating a Belter character. However, if you have access to the Cepheus Engine supplement Uranium Fever: Asteroid Mining Rules for the Cepheus Engine from Stellagama Publishing (2018) the Independent Belter, Company Belter, and Planetary Miner careers are well worth the small cost of the product.

For Mars – Hu-ah!

I tend to generate and play Martian characters pretty much as a standard human. Being born, raised or living on Mars for any extended length of time automatically earns the Zero-G skill. Martian Marines, of course, are generated using the CESRD Marine career although I also draw upon materials found in The Clement Sector, in particular the sourcebook Hub Federation Ground Forces.


There are no specific rules in Cepheus Engine or Orbital 2100 for acceleration effects on characters. Looking at “Falling and Gravity “in CESRD (p. 164), we see that on a 1g world, a character suffers 1d6 damage per 2m of fall. The rules further specify that for higher g worlds, multiple the 1d6 by the planet’s gravity number. The Epstein Drive accelerates at 11-G which we can compute as 11d6 damage. The question is the time period in which this damage takes place. Falling is assumed to be instantaneous, but declaring 11d6 damage per combat round (every 6 seconds) does not seem to fit the events of The Drive. This seems excessive because an average character in Orbital 2100 (7 Strength/7 Dexterity/ 7 Endurance) only has 21 damage points until death. The “average” damage from 11d6 is 44, meaning an average character is dead twice over!

Perhaps we should assume the 11d6 damage takes place every space combat round  (1,000 seconds/16.6 minutes) instead? This better reflects the painful, but non-instantaneous death like Solomon Epstein experiences in The Drive. It still seems like an excessive amount of damage guaranteeing a quick character death.

Looking around for a solution, and not finding one in the rules, I suggest a “house rule” that acceleration couches (built with that acceleration gel) absorb some of the damaging g forces. In This New Ocean: A History of Project Mercury, acceleration couches in the Mercury spacecraft were designed to absorb 9G (assumed to be the maximum G at reentry). If we use couches to absorb, say, 10 of 11G, the character will have only 1g of damage (1d6) per space combat round. This means an average human may  last as long as six space combat rounds, or about 100 minutes, before succumbing to the strangling G forces. We could also say that prolonged exposure to high-g, defined as more than 1-G acceleration but less than the 9-G acceleration gel couch rating, will subtract one from the strength and endurance characteristic every 16 space combat rounds (around 4 hours) unless there is a four-round (1 hour) break in acceleration at 1-G or less. This fits with the time period in Leviathan Wakes when talking about acceleration gel.

These Boots Are Made For Walking

One important piece of equipment is The Expanse is Magnetic Boots. Characters with the Zero-G skill automatically can use Mag Boots; other need 1d6 hours to acclimatize. (I’m so tempted here to say that, based on canonical events in the TV series, female characters get an automatic -2 DM on the time roll, but that would be gender biased, eh?)

“Now you just walk around like you’re in pumps.”

Working In Space

When the player characters are in low-G or micro-G environments, I makes sure to use the Orbital 2100 working in space task check unless they are wearing Mag Boots (count as a handhold for the +2 DM) or the ship is moving with at least 0.3-G acceleration. I also enforce the A&F prolonged micro-gravity exposure rule.

Rochinante, Meet Broadsword and Azhanti High Lightning

Ships in The Expanse are built using what I call a “tower-ship” or “tail-sitter” design where the decks are arranged like floors in a building perpendicular to the axis of thrust. Classic Traveller and Cepheus Engine don’t have many designs to reference, but I will point out that the Azhanti High Lightning-class of cruisers (Classic Traveller Game 3 – Azhanti High Lightning) or the Broadsword Mercenary Cruiser (Classic Traveller Adventure 7: Broadsword) are built using a tower-ship/tail sitter design like the Rochinante. If you want to see a Cepheus Engine ship design that uses the tower-ship configuration I recommend you get Ship Files: Atticus Class Freelancer from Moon Toad Publishing (2017). This 100dTon ship is a tail-sitter not that much smaller than the Rochinante….

Courtesy Moon Toad Publishing

The Gygax Rule for GMs – All you need is good rules and good books

Courtesy http://rpglabyrinth.blogspot.com

In my gaming pantheon, I clearly play wargames first, other boardgames second, and role playing games (RPGs) a distant third. Spending-wise, I have bought very few RPG products since April. In the past month I came close to buying two new RPGs but didn’t. Along the way I learned a valuable lesson taught to me by no other than the Godfather of RPGs, Gary Gygax. Gary reminded me that RPGs are inherently a personal creation; if a product is “not quite right” there are tools available to “do it my way.”

The big RPG splash of the month was the Kickstarter launch of The Expanse Roleplaying Game from Green Ronin Publishing. The project currently (as I write) has over 3,330 backers pledging upwards of $239,000 against goal of $30,000 – and 24 days to go.

I initially pledged to support at the Ship’s Boat-level which is $20 for the pdf version. I then downloaded the free Quickstart pdf and took a look. I am no hard-core The Expanse fan but I generally like the universe. I initially missed the books and became acquainted with the setting through the TV series. After looking at the Quickstart I mulled it over for a few days and then cancelled my pledge.

First, the Quickstarter did not appeal to me; indeed, it actually turned me off. My initial negative reaction was to the artwork. I think my expectations are biased from the TV series and the artwork in the Quickstarter just feels too different. More importantly, it is not what I see as evocative of the setting. It almost seems too cartoonish to me whereas I imagine The Expanse though a more hard sci-fi lens.

Courtesy The Expanse RPG Kickstarter

Secondly, the RPG core mechanic (based on Green Ronin’s Adventure Game Engine – AGE) just didn’t capture what I think feels like The Expanse to me. I admit I was a bit confused at first because I was expecting to see the Chronicle System used in A Song of Ice and Fire Roleplaying Game which is my only other exposure to Green Ronin. I really like the Intrigue Mechanic in Chronicle and it perfectly captures (is evocative of) the Game of Thrones setting.

Looking at the Quickstarter pdf, I weighed my pledge and thought about what I was getting. I decided that I actually already have a version of The Expanse RPG. I actually have two of them, both from Zozer Games, and both using a system I am comfortable with (Cepheus Engine):

  • Orbital: 2100 – “Realistic spacecraft, using reaction drives and rotating hab modules for gravity. Orbital is set in our own Solar System and has a real hard-science feel to it.”
  • HOSTILE – “A gritty near future setting inspired by those late-70s and early 80’s movies like Alien, Bladerunner and Outland.”

I seriously weighed getting The Expanse RPG if not for the system then for the setting material. Then I (fortuitously?) came across this article by Gary Gygax himself and published in 2001 where he talks about author Jack Vance and the Dying Earth books. In particular, Mr. Gygax writes:

There is a truly great advantage offered to the Game Master when devising a campaign set on the Dying Earth. It is not highly detailed. There is no strict timeline laid down. All that has happened before is not “recorded”, nor is there an accurate gazetteer of for the world. What magic operates? Nobody can say or guess, because in the long eons of the Dying Earth’s history, likely every form possible was discovered, used, and then forgotten…almost. That means that all that’s necessary is to have the game in hand, the books that Jack Vance wrote about the world, to create a really compelling campaign environment. Using the creative base of the author, the GM’s own imagination cannot fail but to rise to the occasion. (Emphasis mine)


In my mind, I already own The Expanse RPG. My version uses a core mechanic that I feel is evocative of the setting (Cepheus Engine). I have the sourcebooks in the form of several TV seasons and multiple books and short stories. I don’t need somebody else’s vision that doesn’t strike me as evocative of the stories or setting.

The second RPG I nearly bought was another Kickstarter campaign. Tachyon Squadron from Evil Hat Productions is basically Battlestar Galactica with the serial numbers filed off rendered using the Fate Core system:

Tachyon Squadron is a Fate Core supplement that blends space opera and military sci-fi. It’s Evil Hat’s take on popular stories about interstellar battles, like the ones that have ships with wings named after letters and the one where robots chase the human race through space. If you’re interested in deep space dogfights, friendly—well, usually—rivalries with fellow pilots, and playing scrappy underdogs with the deck stacked against you, this game is for you.

Courtesy Evil Hat

The project funded with 1,401 backers pledging $25,295 against a $7,500 goal. Like The Expanse RPG Kickstarter, Evil Hat was very generous and offers a free download Quickstarter version. It is pretty much as I expected as Evil Hat has previously sold a smaller, similar setting found in Fate Worlds Volume One: Worlds on Fire. In Kriegszeppelin Valkyrie the PCs are pilots aboard a giant War Zeppelin taking on “a horde of WWI mechanical monstrosities.” For Tachyon Squadron I actually was more interested in Stretch Goal 7:

STRETCH GOAL 7 (UNLOCKS AT $26,000): The Battle of Britain: At $26,000, we’ll start work on The Battle of Britain, a 5,000 word electronic supplement that applies Tachyon Squadron’s dogfighting rules to a WWII squadron of Spitfire pilots defending Britain. This supplement will include plane stats and mechanics to help you take to the skies with the Allied forces.

Alas, this stretch goal didn’t unlock. My potential Pilot-in-Training pledge of $12 would not have made a big difference.

What really turned me off about Tachyon Squadron was the over-the-top SJW proselytizing. It is so in-your-face I think it overwhelms the game setting. Even if I am able to put the SJW part aside I see the the game offering me little new. The major rule of difference, dogfighting, is likely not far from that found in Kriegszeppelin Valkyrie which I already own. Much like The Expanse, I have a Battlestar Galactica RPG in the form of the officially licensed Battlestar Galactica Role Playing Game (Margaret Weis Productions, 2007). This game uses the CORTEX Classic system which I generally like (indeed, I am still awaiting my CORTEX Prime: A Multi-Genre Modular Roleplaying Game Kickstarter to deliver – only 3 months overdue…so far). If I want to do Battlestar Galactica using Fate Core I already own all the setting and rules material; why should I invest more money into a near-version that alleges to be ruleset but comes across more like a SJW propaganda tract?

Passing on The Expanse RPG (Green Ronin’s AGE System) and Tachyon Squadron (Evil Hat’s Fate Core System) got me thinking about the games and systems I do have. Last June I listed Star Wars The Edge of the Empire RPG (Fantasy Flight Games) as one of my Top 3 RPGs. I like the Narrative Dice System and want to play more with the RockyMountainNavy Boys. Thinking about expanding beyond Star Wars I picked up GENESYS: The Roleplaying Game for All Settings.

Genesys is a role playing system designed for flexibility and adaptability, specifically tooled to work with any setting imaginable. The Genesys Core Rulebook not only contains an overview of the rules and how the innovative narrative dice system works, but everything a GM and players need to run adventures in five completely different settings. Everything from equipment to adversaries, character abilities to an overview of narrative tropes, all is provided in the core rulebook for Genesys. With a system so adaptable and expansive you can explore every popular roleplaying genre, from classic fantasy style campaigns, to modern day detective thrillers, and even to a far off sci-fi future, Genesys doesn’t fit into any one genre of roleplaying, and instead invites players to craft their own stories with unparalleled freedom.

Taking GENESYS and combining it with Gary Gygax’s Dying Earth GM approach, I can likely make a version of The Expanse or Battlestar Galactica – or any other setting I chose to explore – for myself.

The most important RPG lesson I learned this month is that I don’t need Kickstarter to make an RPG for me that “isn’t quite right”; I just need good books and a good ruleset.

#RPGaDay 2017 – Which RPG have you played the most since August 2016?

#RPGaDay August 4, 2017

pic3089588_tAlthough it is not reflected in in my RPGGeek play records, the RPG I have played the most since August 2016 is Cepheus Engine, and in particular the The Clement Sector setting, Orbital 2100 (as an exploration for The Expanse), and tried These Stars are Ours! I also had more than a little bit of time invested in Star Trek Adventures but gave up two-thirds of the way thru the playtest for lack of excitement.

#RPGThursday – My new Top 10 RPG (March 2017)

I was updating my RPGGeek collection and noticed that my Top 10 was way out of date. Made me start thinking again about which games I like and why.

#10 – Star Wars: Edge of the Empire

pic1545989_mdAt first I was confused by all those fancy dice with their crazy symbols. Now I see this system as one of the best matches of narrative gameplay and setting. I don’t see any other way to play a cinematic science fiction adventure. The nearly-identical Age of Rebellion and Force and Destiny round out the trilogy of adventure just like the original trilogy of movies did. Although low on my list, I am the GM in a campaign for the RockyMountainNavy Boys using this system.

#9 – Mindjammer: The Roleplaying Game (Second Edition)

pic1972069_tI always thought I would not enjoy transhumanism settings in my sci-fi RPG adventuring. At least, that was until I found the FATE Core-driven Mindjammer. Another exploration into narrative-driven RPG systems. (Avoid the Mongoose Traveller version.)

#8 – Traveller5

pic1550426_tMore a guilty pleasure than a game I play. Many people deride the rules but this is my go-to version of Traveller when I want to do some hardcore setting creation. Actually, as long as one avoids Melee Combat the rules hold up surprisingly well. It’s a shame this one gets so much bad press, the game is actually very good – its the bad reputation the first rulebook got that I think makes people stay away.

#7 – Firefly Roleplaying Game

pic1978226_tDriven by the Cortex Plus system, this is another game that shows my tilt towards more narrative-driven games. The setting is also in keeping with the Original Traveller Universe (and not all that far from Edge of the Empire either). The production quality of the books are so shiny!

#6 – FATE Accelerated

pic2026320_tStrictly rules, this slimmed down version of FATE Core is the best rules set I have found to introduce new players to narrative RPG gaming. Some people accuse this game of being too simple; I disagree and say it is the ultimate “rules-lite” system.

#5 – Atomic Robo

pic2005630_tAtomic Robo is a fine example of what happens when authors and game designers are of the same mind. The rulebook is one of the best I have ever seen, effortlessly taking source content and marrying it to game system and examples. The Brainstorming Rules are absolutely essential to ANY narrative-driven game played.

#4 – James Bond 007

pic532310_tGoing old-school here, but James Bond 007 has stood the test of time. The Chase rules, where one bids for initiative is very cinematic. I now recognize that this was the first RPG I played that had a Game Economy in the form of Hero Points. There is also the best-ever Example of Play which puts iconic scenes from the movie Goldfinger opposite game play.

#3 – Cepheus Engine System

pic3217788_tCepheus Engine is the modern 2d6 Sci-Fi RPG system that is the natural evolution of Classic Traveller. Except this one uses the Open Game License and not Mongoose Traveller’s much more restrictive legal obstacles to third-party publishing. Though a youngster, there are several great settings that take advantage of they rules including the awesome The Clement Sector, Orbital 2100, and the brand-new These Stars are Ours!

#2 – Diaspora

pic536195_tDiaspora uses the older FATE 3.0 engine, and could probably use an update to FATE Core. But the designer’s don’t have to be in a rush because Diaspora is a great game as-is. Occasionally called the Traveller version of FATE, I love it for many of the same reasons I love Traveller; it is a sci-fi adventure RPG with moderate rules overhead. The Space Combat rules are a unique take on vector-combat using range bands (and should be retrofitted to Classic Traveller).

#1 – Classic Traveller

45b96a0a8845ed78b2958bc87f1b6b58_largeIt was 1979 that I first discovered roleplaying games, and my gateway game was the three Little Black Books of Traveller. Who can ever forget the simple text on the box cover:

“This is Free Trader Beowulf, calling anyone…Mayday, Mayday…we are under attack…main drive is gone…turret number one not responding…Mayday…losing cabin pressure fast…calling anyone…please help…This is Free Trader Beowulf…Mayday….”

Now known as Classic Traveller, the rules are still a model of “complex simplicity.” Complex in that all the tools for making your own adventure are there (there is no default setting or Third Imperium in the original LBBs) and simple in terms of rules. Maybe a bit too simple, as shown by the modern rules version in Cepheus Engine. It really doesn’t matter to me what today’s version is called, Classic Traveller will always be the one dearest to my heart.

All images courtesy RPGGeek

#TSAO These Stars Are Ours! A setting for #CephesusEngine or #TravellerRPG



Courtesy spacecockroach.blogspot.com
These Stars Are Ours!  (TSAO) is a tabletop RPG Sci-Fi setting for the Cepheus Engine or 2D6 OGL SCIFI (nee Traveller SRD). TSAO is a complete Alternate Traveller Universe (ATU) small-ship setting that offers rich background, interesting aliens, and many adventure seeds for the Referee. Though not without a few warts, TSAO shows the great potential of Cepheus Engine used in a setting beyond the classic Third Imperium.  TSAO may be the first setting to take full advantage of the Cepheus Engine rules from the ground up and joins Gypsy Knight Games The Clement Sector and Zozer Games Orbital 2100 as yet another example of the vibrant Cepheus Engine community of rules and settings.



The setting of TSAO is a logical outgrowth of 20th century UFO conspiracies:

Set in 2260 AD – two years after the Terrans took Keid and forced the Reticulan Empire to capitulate the book introduces the player characters to the immediate aftermath of the Terran victory in the Terran Liberation War against the mighty Reticulan Empire and its many thralls. For their part, the upstart Terrans, bolstered by their victory against their old masters, now move to become a power to be reckoned with in interstellar affairs. Against this background of espionage, maneuvering, and saber-rattling, and on the new interstellar frontiers, the player characters can forge a destiny of heroes or villains of the new United Terran Republic. (DriveThruRPG)

TSAO is delivered in a 209 page pdf (also now available in a POD option). This meaty setting is explained over six chapters and two appendixes.


Courtesy spicapublishing.co.uk
Chapter 1 – The United Terran Republic provides much of the history and setting background. Included is not just a recap of events to date, but also many groups or factions or agencies that the player characters (PCs) could interact with. Psionics has a role in this setting. Given the assumed Tech Level (TL) of 11-12 (with some military at 13), TSAO (like Omer Golan-Joel’s earlier Outer Veil setting) is a high-tech but small-ship universe.


Chapter 2 – Aliens describes the humans neighbors, opponents, and allies(?). In the space of just a few pages many races are fully described and (again) are rich with adventure seeds and story hooks for development.

Chapter 3 – Characters and Careers is a great example of how to take the basic character generation system in Cepheus Engine and stretch it to showcase it’s full potential. PCs can be the default Humans or select from several alien races. Careers are taken from 13 civilian careers in Cephesus Engine or an from the 20 new ones in TSAO, including seven (7) alien “careers.”

Courtesy spacecockroach.blogspot.com
Chapter 4 – Starships showcases alien saucers and Terra’s ships along with a few other alien constructs. Art is provided by the ever-dependable Ian Stead and others. Make sure to look at the 300-ton Terran Shaka-class Light Military Transport (and especially the Decommissioned Shaka-class Transport) for a not-to-subtle nod to Serenity and the Firefly-class.

Chapter 5 – Terran Borderlands is combination gazetteer and Referee’s Information. The worlds of Known Space is detailed, along with many story hooks and adventure seeds. The usual World Generation process from Cephesus Engine is expanded upon here with an Expanded Universal World Profile that adds a bit more detail but also a whole many more ideas that PCs or Referees can grab onto.

Chapter 6 – Patrons describes 12 Patrons that might engage the PCs. The chapter is not only a grouping of ready-made adventures, but also provides insight into the setting as viewed by the authors.

Appendix A – Terran News Agency Dispatches, February 2260 is a call back to the Traveller News Service snippets that were a staple of Classic Traveller and its successors. Again, these short news items can be the start of yet more adventures!

Appendix B – Sources of Inspiration, Literary and Otherwise is TSAO‘s Appendix N. I always look over these lists to see what inspirations the authors took and to see what I may want to add to my reading/viewing.

The last part of TSAO is an index. This is one of the best indexes I have ever seen in a book. However…the pdf is not cross-linked. This highlights some of my pet peeves with so many pdf products; page numbering and no linking. TSAO is paginated like most books, with page 1 being the interior title page. Unfortunately, this is “page 3” of the pdf, meaning if using your pdf page search you will always be three pages off from your target! The publisher could of avoided (or lessened the impact) of this issue if the Table of Contents (or even that great Index?) was linked.

Production quality is very good. Compared to Stellagama’s previous The Space Patrol I can see definite improvement. Get the linking and page numbering issues nailed and I will likely have nothing to complain about….

The authors call TSAO the first in the Visions of Empire (VoE) space opera settings. If TSAO is any indication, the VoE series will be settings rich in background using (and stretching) the Cepheus Engine rules to their finest.


These Stars Are Ours!  By Omer Golan-Joel, Richard Hazelwood, and Josh Peters. Stellagama Publishing, 2017.

#TheExpanse Ships in #TravellerRPG

Watching “Home” (The Expanse, Season 2, Episode 5) with the Rocinante at high-g burns got me back to thinking about the ships of The Expanse and how they could be portrayed in tabletop RPGs. I previously looked at the Epstein Drive and how it might be translated into game terms for use in Traveller RPG or Cepheus Engine or Orbital 2100.

**WARNING – Minor Spoilers Ahead**

Courtesy SyFy

Going all the way back to the first book in the series, Leviathan Wakes, the small shuttle Knight gives us some insight into the technology of The Expanse:

It wasn’t long before Alex called down, “Okay, Boss. It’ll be about a four-hour trip flying’ teakettle. Total mass use at about thirty percent, but we’ve got a full tank. Total mission time: eleven hours.”

“Copy that. Thanks, Alex,” Holden said.

Flying teakettle was naval slang for flying on the maneuvering thrusters that used superheated steam for reaction mass. The Knight‘s fusion torch would be dangerous to use this close to the Canterbury and wasteful on such a short trip. Torches were pre-Epstein fusion drives and far less efficient. (Leviathan Wakes, Chapter 3)

From the book we know that the trip covers 50,000km. Working with classic space travel time equations, we can compute the Knight is traveling at about 1.0368 m/s or just over .1G acceleration.

Later in Chapter 5 we see the Knight running flat-out at 2G acceleration. At this speed the same 50,000 km trip should take only 53 minutes, which is a bit shorter than the approximately 70 minutes obliquily stated in the book. At this point it is unclear if the 2G speed is the upper limit of the teakettle or the fusion torch at low power.

The Knight does eventually clearly light it’s torch:

“Roger that, XO. Bleeding-g burn-and-flip laid in. Angled approach course so our torch won’t burn a hole in the Cant. Time to rock and roll?” Alex replied. (Leviathan Wakes, Chapter 5)

Courtesy NBC Universal

Here we have to interpolate the fusion torch acceleration based on Holden and his apparent weight. When lighting the torch Holden weighs 500 kilos. Assuming he is an average 75 kg to begin with, this works out to almost 7G. Interestingly, from the novella The Drive we know that 7G is the instrument limit on Solomon Epstein’s ship that he installed his new drive on, indicating that the fusion torch may have an upper limit of 7G.

In summary, we can say the shuttle Knight has maneuvering thrusters (teakettle) that operate efficiently at .1G. The shuttle also has a fusion drive (torch) that can accelerate it at up to 7G.

The Knight‘s torch drive could deliver a lot of thrust, but at the cost of a prodigious rule-burn rate. But if they could save the Cant, it wouldn’t matter. (Leviathan Wakes, Chapter 5)

The missiles that are fired at the Canterbury are also very impressive:

As if in answer, six new objects appeared on his radar, glowing yellow icons appearing and immediately shifting to orange as the system marked their acceleration. On the Canterbury, Becca yelled out, “Fast movers! We have six new high-speed contacts on a collision course!”

“Jesus H. Christ on a pogo stick, did that ship just fire a spread of torpedoes at us?” McDowell said. “They’re trying to slap us down?”

“Yes, sir,” Becca said.

“Time to contact.”

“Just under eight minutes, sir,” she replied. (Leviathan Wakes, Chapter 5)

For these six missiles to cover 200,000km in 8 minutes means their acceleration has to be around 150G!

In Leviathan Wakes, Chapter 51, Holden tries to remember how fast the Roci can go:

He tried to remember the Roci‘s maximum theoretical acceleration. Alex had already flown it at twelve g briefly when they’d left the Donnager. The actual limit was one of those trivial numbers, a way to brag about something your ship would never really do. Fifteen g, was it? Twenty? (Leviathan Wakes, Chapter 51)

Courtesy solotalkmedia.com

In the episode “Home” if I caught the screen correctly it looks like the Roci was accelerating just over 17g. This again is in line with the book; and way faster than the 6g of Classic Traveller or Cepheus Engine and far ahead of the technology in Orbital 2100 where the alternative Nuclear Pulse Fusion Drive tops out at 1.2g! Compared to the Traveller RPG or Cepheus Engine universe, the ships and weapons of The Expanse are way faster and likely far more deadly too.

As late to the game as I am, I look forward to reading more of The Expanse series and seeing what further ship secrets are hidden within.

PS: The math for figuring time and acceleration is actually easy, but to help there is an EXCELLENT site at http://www.transhuman.talktalk.net/iw/TravTime.htm that does the math for you!




#RPGThursday -To the Far Horizon with Atlas

Two of my three favorite Traveller RPG, uhh…”2d6 Classic Sci-Fi RPG”, companies published new items recently that I acquired.

202309-thumb140The first is Far Horizon from Zozer Games. The cover calls it Far Horizon: A TL9 Exploration Ship for the Cepheus Engine whereas the front matter states Far Horizon: A Near Future Mission and Spacecraft for Cepheus Engine. Both titles are correct, although the second one is more accurate. This title is designed to go with the Zozer’s Alternate Traveller Universe (ATU) setting of Orbital: 2100 although everything is included here to play this adventure with just the basic Cepheus Engine rules if needed. pic3217789_mdInside one finds not only background into the mission but also a complete description of the DRV Far Horizon, a nuclear-thermal rocket for exploring deep space. Included also are rules for TL9 Vacc Suits. The adventure itself is a race-against-time investigation into the unknown.

109517-thumb140Parts of Far Horizon have been available previously. The ship itself is a free download at DriveThruRPG. The rules on vacuum suit construction were in a previous product, Vacc Suit, which is no longer available no-thanks to the Mongoose Publishing Community Content Agreement. So it is refreshing to see this packaging bringing back good near-future, hard-ish sci-fi adventure! Adding to the quality, the product is nicely illustrated by Ian Stead and others.

If one has looked at Orbital: 2100 but are not sure about making the jump into this ATU, Far Horizon is a great way to try out the setting.

202134-thumb140The second product I got was Ships of the Clement Sector 17: Atlas-class Freighter from Gypsy Knights Games. This is the second of what I call “expanded” ship books from GKG. The 50-page product includes excellent narratives to set the mood, awesome ship art by Ian Stead (again), and just enough adventure seeds to whet a GM’s appetite. Indeed, this larger format allows for more of each giving both players and GMs more to think about and more potential for adventure. If you are a fan of The Expanse, you may find a similar vibe to that universe and some of the stories and background presented here. Though many might look at an 800 dT freighter as “not sexy enough to be my ship,” the reality is it takes ships like the Atlas to ply the shipping lanes of the Clement Sector and ekk out a living. This book helps your players do just that. Another must-buy from GKG!

All images courtesy DriveThruRPG.

Far Horizon, ©2016 Zozer Games.

Ships of the Clement Sector 17: Atlas-class Freighter, ©2017 Gypsy Knights Games, LLC.


#RPGThursday – Rucker Patrol

Two RPG items I got over the holidays were Ships of the Clement Sector 16: Rucker Class Merchant (Gypsy Knights Games) and The Space Patrol (Stellagama Publishing). Long-time Traveller RPG fan Alegis Downport already posted his views of each so I direct your attention to his excellent comments (Rucker / Space Patrol) and will just add a few more thoughts of my own.

pic3293444_mdMake sure you read both parts of Alegis Downport’s comments on the Rucker since he had a very intimate hand in the creation of the ship. There is nothing more I can add except to heartily endorse all the kudos he gives to Gypsy Knights Games for bringing Ships of the Clement Sector 16: Rucker Class Merchant to market. SotCS 16 continues a great line of useful products from Gypsy Knights Games that are at home in any Traveller RPG setting. Thanks to Alegis Downport, users of the ship now have even more thought-seeds for adventure.

pic3238660_mdMy praise for The Space Patrol is a bit more reserved. The Zhodani Base named The Space Patrol their “Best ATU Setting” for 2016. As much as I like Zho, I must respectfully disagree. Although I find The Space Patrol a very interesting career and a welcome addition to any setting, I feel that pic3217789_mdOrbital: 2100 (Zozer Games) is a much better example of how to take the original Traveller 2d6 sci-fi system (as detailed in Cepheus Engine) and use it to make an exciting Alternate Traveller Universe. I also feel that The Space Patrol suffers from some poor formatting decisions (like more-that-a-few tables that cross pages) that make it feel a bit too DTP-like in an era where small publishers (like Gypsy Knights Games) push out very high quality products. But don’t get me wrong – The Space Patrol is a great addition to any Traveller/2d6 Sci-Fi/Cepheus Engine setting and should be in everyones collection. I just wouldn’t have given it the coveted ATU Setting of the Year. 

All images courtesy RPGGeek.

Ships of the Clement Sector 16: Rucker Class Merchant, ©2016 Gypsy Knights Games.

The Space Patrol, by Richard Hazelwood, ©2016 Stellagama Publishing.

Orbital: 2100 – A Solar System Setting for the Cepheus Engine, by Paul Elliot, ©2016 Zozer Games.

#TheExpanse #TheDrive in Orbital 2100 – #TravellerRPG & #CepheusEngine Mods

In a previous post, I discussed the role-playing game Orbital 2100 – A Solar System Setting Using the Cepheus Engine Game and how it could possibly be used for playing in The Expanse setting. In The Expanse, the Epstein Drive is the engine that powers spacecraft across the Solar System. But just how does the Epstein Drive perform, and how could it be portrayed in the Orbital: 2100 setting using Cepheus Engine?

When playing Traveller or today’s Cepheus Engine games like Orbital 2100, I tend to be (using Marc Miller’s definitions from T4) a “Detailed Role Player.” I stray into the “System Engineer” role at times, like for this post. Part of my intention here is to show RPG players and referees/GMs that “this isn’t rocket science” – between the setting, game rules, and the internet (and with the help of a spreadsheet/calculator) it is actually fairly easy to do this analysis.

Fortunately, we have a “canon” story that we can draw inspiration from. The novella The Drive (published in 2012 and available for free online) takes place 150 years before the events of the first novel in the series, Leviathan Wakes. The Drive tells the story of Solomon Epstein, the inventor of the Epstein Drive. It is a very short novella coming in at a mere seven pages. Those seven pages, however, give us plenty of information that can be used to derive the performance of the Epstein Drive.

“By the way, we’re accelerating at four gravities. Five. Six. Seven.”

“He wonders how much above seven he’s going. Since the sensors are pegged, he’ll have to figure it out when the run is over.” – p. 1

In the first pages of the novella, we find a common language between the novels and the Orbital 2100 setting. Like Cepheus Engine and the Traveller RPG it derives from, spacecraft performance is expressed in g’s of acceleration. One g (1g) of acceleration is 9.8 meters/second/second. [Cepheus Engine and Traveller round this to 10 m/s/s…but we will use the actual value for the purposes of this discussion] Seven g’s of acceleration works out to 68.6 m/s. Since Sol’s “sensors are pegged,” this passage also establishes an instrumentation limit of the time.

“The yacht is built for long burns, and he started with the ejection tanks at ninety percent. The readout now shows the burn at ten minutes. The fuel supply ticks down to eighty-nine point six. That can’t be right.

Two minutes later, it drops to point five. Two and a half minutes later, point four. That puts the burn at over thirty-seven hours and the final velocity at something just under five percent of c.” – p. 1

These passages help determine a fuel consumption rate.

  • Using the 90% full tank as a beginning, and given that after 10 minutes 89.6% remains, we see that .4% was consumed in that short time for an hourly consumption rate of 2.4%.
  • “Two minutes later,” or after 12 minutes of total burn, the tanks are 89.5% full; meaning that .5% has been consumed at a rate of 2.5% per hour.
  • Finally, after 2.5 minutes more – or 14.5 minutes total – the tanks are at 89.4% full, or .6% consumed for a rough consumption rate of 2.4% per hour.

Using the 2.4% rate, 90% divided by 2.4% gives us 37.5 hours of “burn” endurance – right in line with Solomon’s “over thirty-seven hours” statement.

The later passage helps compute the acceleration performance of the Epstein Drive.

  • The speed of light – c – is 299,792,458 m/s. Five percent (5%) of c is 14,989,623 m/s.
  • The formula for acceleration is a=v/t where a equals acceleration in m/s, v is velocity in m/s, and t is time in seconds.
  • Plugging in our numbers for velocity (5% of c) and time (37.5 hours or 135,000 seconds) we get an acceleration of 111.03424 m/s.
  • Dividing this by 9.8 m/s, we get 11.33g acceleration.

Eleven g’s of acceleration is quite a lot, even for Cepheus Engine/Traveller where a top-grade maneuver drive is no more than 6g performance!

“Only the acceleration isn’t the problem either. Ships have had the power to burn at fifteen or even twenty g since the early chemical rockets. The power is always there. It’s the efficiency necessary to maintain a burn that was missing. Thrust to weight when most of your weight is propellant to give you thrust. And bodies can accelerate at over twenty g for a fraction of a second. It’s the sustain that’s killing him. It’s going for hours.” – p.3

NASA and the military conducted many experiments in the 1950’s and 1960’s that established a 20g human limit to acceleration. Sol is obviously in pain, but in terms of Cepheus Engine and Orbital: 2100, just how much damage is he taking?

There are no specific rules in Orbital 2100 for acceleration effects on characters. Looking at “Falling and Gravity “in Cepheus Engine (p. 164), we see that on a 1g world, the character will get 1d6 damage per 2m of fall. The rules further specify that for higher g worlds, multiple the 1d6 by the planet’s gravity number. The Epstein Drive accelerates at 11g, which we can compute as 11d6 damage. The question is the time period in which this damage takes place. Falling is assumed to be instantaneous, but declaring 11d6 damage per combat round (6 seconds) does not seem to fit the events of The Drive. This seems excessive because an average character in Orbital 2100 (7 Strength/7 Dexterity/ 7 Endurance) only has 21 damage points until death. The “average” damage from 11d6 is 44, meaning the character is dead twice over!

Perhaps we should assume the 11d6 damage takes place every space combat round  (1,000 seconds/16.6 minutes) instead. This better reflects the painful, but non-instantaneous death like Solomon Epstein experiences. It still seems like an excessive amount of damage, guaranteeing character death.

Looking around for a solution, and not finding one in the rules, I suggest a “house rule” that acceleration couches absorb some of the damaging g forces. In This New Ocean: A History of Project Mercury, acceleration couches in the Mercury spacecraft were designed to absorb 9g (assumed to be the maximum g at reentry). If we use couches to absorb 9 of 11g, the character will have only 2g of damage (2d6) per space combat round. This means an average human may  last as long as three space combat rounds, or about 48 minutes, before sub-coming to the strangling g forces.

“Even as he struggles to make the terminal respond, he’s also thinking what the drive means practically. With efficiency like this, ships can be under thrust all through a voyage. Acceleration thrust to the halfway point, then cut the engines, flip, and decelerate the rest of the trip. Even a relatively gentle one third g will mean not only getting wherever they are headed much faster, but there won’t be any of the problems of long-term weightlessness. He tries to figure how long the transit to Earth will take, but he can’t.” – p.5

Ah, here we can use the classic formula for interplanetary travel time where a ship constantly accelerates to a midpoint, flips over, and then decelerates at a constant rate to the destination. The formula is t=2*SQRT(d/a) where like before = time in seconds, = distance in meters, and = acceleration in m/s/s. (see Cepheus Engine, p. 104)

Unlike Solomon, we do not have 11g’s of force crushing down upon us, so we can solve for the time it would take an Epstein Drive spacecraft to travel from Mars to Earth.

To figure distance, one must first realize that both Mars and Earth orbit the sun differently and the distance between the two planets is not constant. At opposition, the two can be as close as 56 million kilometers (Mkm); however, at conjunction the two can be as far as 401 Mkm apart!. On average, Mars and Earth are 225 Mkm apart.

[Interestingly, in Cepheus Engine, Chapter 6: Off World Travel, Interplanetary Travel, Table: Common Travel Times by Acceleration, there is a listing for “Far Neighbor” with a distance of 255 million km. This is close enough to the Earth-Mars average distance that I think it was the source for the entry. Orbital 2100, Chapter 6: Operating Spacecraft, Travel Times, Travel Between Inner Planets, uses a different process to determine distance (p. 71). In Orbital 2100 you start with the Basic Distance of 80 Mkm (Inner Planets: Basic Distance Table) PLUS seven squares of travel on the Travel Between Inner Planets chart (using the recommended starting setup). This works out to a total travel distance of 290 Mkm – within reason but a bit above the average.]

For the purposes of this example, lets use the 225 Mkm average. Using that average distance (225 Mkm), and Sol’s stated  1/3g (3.27 m/s acceleration), the formula gives us a travel time of Mars to Earth of just over 3 weeks. This may be a normal pre-Epstein Drive trip, given the 3.27g falls within the previously noted 7g instrument limit.

“The United Nations ordered that all shipyards on Mars shut down until an inspection team could be sent out there. Seven months to get the team together, and almost six months in transit because of the relative distances of the two planets in their orbits around the sun.” – p. 6

From this passage we can assume that Sol is telling us that the average transit time between Earth and Mars is about six months. The is an important figure to remember for later.

“And the war! If distance is measured in time, Mars just got very, very close to Earth while Earth is still very distant from Mars. That kind of asymmetry changes everything.” – p. 7

Once again, lets assume the Earth to Mars distance d to be 225 Mkm. Using the Epstein Drive with an acceleration of 11g ( a=111.03424 m/s) and solving for time t gets 12.5 hours. This is a major difference from the six months Sol was thinking about earlier. It is orders of magnitude better performance!

Think for a moment about Jupiter like Sol does. Assuming the Earth-to-Jupiter average distance is 588 Mkm, using the Epstein Drive the trip would take 1 day and 16 hours!

In Orbital 2100, the best TL 9 Nuclear Thermal Rocket (NTR, p. 41) can only travel a maximum of 330 Mkm per month, meaning it takes 1 month and 23 days to make the Earth to Jupiter transit. Even the best alternative TL 10 Fusion Drive, or Nuclear Pulse Fusion (NPF, p. 61), has an acceleration performance of 12 m/s for a travel time of 5 days and 21 hours. Even the best performing Maneuver Drive in Cepheus Engine (6g or 60 m/s acceleration – p. 122), takes 2 days and 7 hours to make the same trip.

Unfortunately, as much as we can learn from The Drive about Epstein Drive performance, the novella lacks other details like the size of the drive or the volume of fuel required. This means we will have to look elsewhere for that information, like maybe Leviathan Wakes.

In summary, the Epstein Drive is very efficient compared to the NPR and NTR in the Orbital 2100 setting. Even compared to maneuver drives available in Cepheus Engine the Epstein Drive is superior. The major drawback, as Sol discovered, is the crushing gravity of acceleration. In the default Traveller setting, the Original Traveller Universe, this is overcome by using handwavium acceleration compensators. In The Expanse, 150 years after Sol’s invention, you have “the juice.”

The juice was a cocktail of drugs the pilot’s chair would inject into him to keep him conscious, alert, and hopefully stroke-free when his body weighed five hundred kilos. Holden had used the juice on multiple occasions in the navy, and coming down afterward was unpleasant. –Leviathan Wakes

Leviathan Wakes, Copyright (c) 2011 by Daniel Abraham and Ty Franck.

The Drive (A Novella for The Expanse), Copyright (c) 2012 by Daniel Abraham and Ty Franck.

Cepheus Engine: A Classic Era Science Fiction 2D6-Based Open Game System. Copyright (c) 2016 Samardan Press.

Orbital 2100 Second Edition, Copyright (c) 2016 Zozer Games.

“The Traveller game in all forms is owned by Far Future Enterprises. Copyright 1977-2016 Far Future Enterprises.”

#RPGThursday #Orbital2100 RPG #CepheusEngine Chargen

Using Orbital 2100: A Solar System Setting of the Cepheus Engine I ran thru a character generation example. As I talked about in a previous post, Orbital 2100 makes only minor changes to the standard Cepheus Engine character generation process.

Meet Vanov Page, idealistic young man born aboard LSC-1 Mattias Vanderveen in Earth orbit at L4.

STR 4 (DM-1) / DEX 9 (+1) / END 4 (DM-1) / INT 9 (DM+1) / EDU 3 (DM-1) / SOC 6

Background skills are as in Cepheus Engine (3+ EDU DM). However, one must be taken from the Orbital 2100 Background Skill table (p. 31). Vanov, coming from an Orbital Colony, gains Mechanics 0, as well as Computer 0.

Choosing a Mining and Colony Survival campaign, Vanov becomes a Surface Operator. The equivalent Cepheus Engine career is Colonist.

First Term: Survives. As Rank 0 gains Survival 1. Does not commission nor advance. Service Skills gained are Mechanics 0 (already possessed), Gun Combat 0, Animals 0, Electronics 0, Survival 0, and Vehicle 0. After an eventless first term, Vanov reenlists.

Second Term: Survives. This time Vanov commissions as an Officer (Rank 1 – District Leader) and gains the skill Jack-of-all-Trades! After gaining an additional service skill in Vehicles, he now has Vehicle (Ground ) 1. Vanov also successfully advanced this term (Rank 2 – District Delegate) and picks up Gun Combat, making his skill Gun Combat (Slug) 1. Riding high on his success, Vanov reenlists again.

Third Term: Survival roll is END 6+, and thanks to Vanov’s DM-1 he FAILS. Rolling on the Injury Table, we find Vanov was severely injured which reduces one physical characteristic by 1D6. Rolling a 5 (super ouch!) Vanov reduces his END from 9 to 4 with a new DM -1. Per Cepheus Engine, Vanov must now leave the service after an abbreviated term (2 years) and will get no benefit roll this term.

Mustering Out: Vanov gets two benefits rolls. He takes one on the Orbital 2100 Universal Benefits Table (p. 35) and gets +1 SOC. His cash benefit is 4,000Cr. Per the Orbital 2100 rules, this is reduced to 10% of the Cepheus value, or  400Cr.

At this point I review Cepheus Engine and look at the rules for Medical Care (p. 29). Restoration of a lost characteristic is 5,000Cr per point. Raising DEX to 6 (2 points) would cost 10,000Cr and void the DM -1. Rolling on the Table: Medical Bills (p. 30) results in “the company” covering 50% of the cost, but this leaves Vanov having to cover the other 5,000Cr. I figure this is a good character aspect; Vanov is in debt and therefore more likely to be “asked” to do provide “interesting” tidbits of information.

Vanov Page, Age 28, ex-Colonial District Delegate (Medically Retired, now available as a Contract Advisor). 400Cr.

STR 4 (DM-1) / DEX 6 / END 4 (DM -1) / INT 9 (DM +1) / EDU 3 (DM -1) / SOC 7

Animals 0, Computer 0, Electronics 0, Gun Combat (Slug) 1, Jack-of-all-Trades 1, Mechanics 1, Survival 1, Vehicle (Ground) 1.

Vanov Page was born in an Orbital Colony above Earth. Although the habitat has some gravity, Vanov is generally frail but very agile in the lower gravity. Raised not to look down but out to the other planets, Vanov decides to become a Surface Operator supporting mines and colonies. His first few years are taken by hard study where he learns the basics of his career. After a few years, Vanov begins to make his mark and quickly rises in rank to District Delegate. But then a great accident befalls him, and he is severely injured. At the depths of his physical misery, Vanov is approached by an old friend who offers to help pay for part of his medical bills in exchange for certain “favors” in the future. Grasping at the slim chance presented to him, Vanov agrees.

Medically retired from colonial government matters, Vanov Page hires himself out as a advisor for small start-up colonial and mining ventures. Vanov is secretly in debt to Tharsis Heavy Industry for “only” 5,000Cr – or so he thinks. He needs to pass along a few real “gems” of information if he ever is to get free of his obligation. The last time Vanov passed on info about a new outpost setting up, Tharsis was able to use the inside information to underbid their competitors and win the contract. Vanov then realized that Tharis planned on using “less-than-optimal” equipment and some of the staff sent were a bit iffy. Vanov wonders if his restored health is worth the risks he is taking….