Tripwire Interactive's support of Killing Floor has been jolly admirable, with regular free content updates and paid DLC releases which don't feel at all cheeky. After taking us to a frightful fairground for its summer event and a mutant hillbilly hideout at Halloween, the co-op survival shooter is blasting players to the Moon, of all places, in its latest 'Twisted Christmas' celebration.

This year, monstrous Christmassy versions of Killing Floor's monsters have swarmed a moonbase, and it's up to you to explode their heads and watch bits of brain float away in low-gravity.

Scattered around the moonbase are pieces of a superweapon you can assemble, and the update adds a new gun for the Medic class too. A new axe is up for grabs as well, if you either earn 40,000 gold in the free-to-play version of Dwarfs!? or own the full version. Plus, of course, this brings another opportunity to unlock the festive Baddest Santa skin.

The update was supposed to hit on Tuesday, but was delayed by a last-minute bug discovery. It is out now, though, and is scheduled to end on January 3. Two new paid cosmetic DLC packs, offering a robotic player character and gold weapon skins, are supposed to launch alongside it. Check the official event page for more details.