Warhammer 40K: Space Marine may be pushing its meaty shoulders into retail this coming week, but its co-op mode won't arrive until "early October" says THQ. The mode, with the Latin-derived name "Exterminatus," will be made free as a download to "all players" according to THQ's release.

Exterminatus contains two separate "scenarios" in which four-player groups can maneuver their bulky trio of classes around, chainsawing through everything in their path. Global leaderboards are also included, posing "dynamic challenges" to players and supporting additional "score modifiers" (read: Skulls).

Some confusion was raised over the game's co-op back in August when a GameStop advert pinned the co-op mode exclusively to GameStop pre-orders, but today's announcement clearly refutes that information.