Relic has detailed co-op for Warhammer 40,000: Space Marine.
As was explained in the initial announcement early last month, the co-op mode, called Exterminatus, won't be available until early October via DLC.
When it does arrive, however, it'll come with two maps allowing four players to work together in a Horde-style game as they battle waves of increasingly difficult enemies.
Two maps may not excite straight away, but it's free and who knows what will be added in the future.
Playing with mates isn't all about flowery co-operation though. Watch a recent Space Marine multiplayer trailer to get an idea of how the killing will work.