Worldkiller is an old SPI/Ares Magazine game published in 1980. I have the boxed version shown here. The game simulates a planetary invasion in the far future.
The game itself is very simple; a double-page size map, four pages of rules, a one-page handout and 100 counters. The map is interesting, being a 3-D representation of space. Each “cube” actually has 7 levels; three above and three below the 0-level plane. In effect, the map represents are area 8x12x7 cubes in size. Located on the map are a single planet and four fortresses protecting it.
One player is the Alien Intruder and the other is the Human Planetary Defender. Ships are rated by attack (range) – defense- and jump range. Combat is a simple 1d6+(Attack-Defense). Ships with damage equal to defense are crippled and must be repaired. If damage is double the defense value the ship is destroyed. Each turn, a ship can take one of four actions; Jump (move), Attack, Pop (a combination move+attack that causes damage to ship) or Repair. For the Intruder there is also Stretch which is a delayed jump but with a longer range. To counter the Intruder special Stretch ability the Human defender can place his ships adjacent to each other for a defensive benefit.
The game is actually very simple; counter density is low and tactics are not all that innovative. The Intruder has longer range weapons and can Stretch but the Human is more numerous and if he uses his ships together he has a defensive benefit. The “gimmick” in Worldkiller is obviously the map; a 2-D representation of a 3-D battle. In many ways the game feels like an experiment in how to make a 3-D space battle game. I say experiment because the game is very rules “lite.” Without the map gimmick the game is unremarkable and unmemorable.
All that said, the gimmick works. The game is simple enough that players concentrate on maneuver; in three dimensions. The very simplicity of the game allows players to enjoy the maneuvering around the cubes. This game should belong in the collection of every serious space-gamer as an example of 3-D movement on a 2-D map.