It's lucky that Christmas is coming, as otherwise nothing would be happening in the world of video games. Killing Floor developer Tripwire today announced the return of Twisted Christmas, an event which transforms the co-op survival FPS into a wintry horrorshow. This being the fourth such celebration, gosh, it's almost a Christmas tradition in itself.

Once again, Twisted Christmas sees Killing Floor's monsters transformed into dreadful snowmen, gingerbread folk, reindeer, elves, ice golems, and other festive freaks. As is tradition, today's update also brings new maps, in the shape of the fan-made Hell and Forgotten. Christmas achievements are back too, so players have another chance to unlock the Baddest Santa character.

This being the giving season, Tripwire's also bringing new things to The Ball, with a new mini-campaign estimated to take two hours. The Ball's protagonist is coming as a playable Killing Floor character for everyone who owns both games, too.

If you're looking to give gifts yourself, Killing Floor and all its DLC and The Ball are 50% off on on Steam until January 2.