Cosmic Encounter is a board game in which three or more players become alien races and compete and cooperate to spread their influence across the universe. The object is for players to, through both war and peace, land their ships on other players' planets, thus establishing colonies on them. Each alien race has a unique power, allowing players to skew different rules of the game to their advantage. Once a player has gained a total of five colonies on other players' planets, they win the game - and because forming and breaking alliances is a core part of the game, it's highly possible for multiple players to win together!
The game was originally released in 1977 and has seen a total of four major versions, each by a different publisher, and one spinoff since then.
- The first edition was published by Eon Productions and released in 1977. It had a total of nine expansion sets from 1977 to 1983.
- The second edition was published by Mayfair Games and released in 1991. It had one expansion set in 1992 and a simplified re-release in 1995. One more expansion for it was planned but never released.
- The third edition was published by Avalon Hill and released in 2000. It had no expansion sets.
- The fourth and current edition was published by Fantasy Flight Games in 2008. It has a total of seven expansion sets and two promotional aliens as of 2022. An updated re-release was published in 2018 in honor of the game's 42nd anniversary.
- A two-player spinoff game, Cosmic Encounter Duel, was published by Fantasy Flight Games in 2020. It is set in the same universe as Cosmic Encounter with the same general gameplay but several mechanisms modified to suit two-player gameplay.