From Wikipedia:
Space Hulk is a board game by Games Workshop, first released in 1989 and re-released in 2009. The game is set in their Warhammer 40,000 universe and draws a certain degree of inspiration from the Alien movies.
The term "Space Hulk", from which the game gets its name, is used within the Warhammer 40,000 universe for any masses of ancient, derelict starships, asteroids, and other assorted space junk drifting in and out of the Warp that eventually merges into one massive form, ranging from the size of a small moon to a large planet, which drift through the territory of the Imperium. Because a hulk may contain bits of lost information or technology, or hostile life forms that pose a threat to mankind, the Imperium often sends teams to search for and secure these entities. The hulk may not stay in real space for very long, eventually slipping back into the Warp, so retrieval operations must be rapid and efficient.
Genestealers often make homes of these hulks, attacking those who come aboard in order to spread their genetic code further afield. The game pits an investigative force of Space Marine Terminators against such a coven.
A third edition of Space Hulk was released by Games Workshop on September 5th, 2009.