Tripwire has announced that the cast of its Killing Floor Summer Sideshow event are back in for a Halloween event and dressed up as monsters. From now until November 3, Frankenpound, Husk-O-Lantern, Werebunny are running about the place, and you can earn a new batch achievements, set in Bedlam as an added fun bonus. Apparently, once you complete these achievements, you’ll unlock the Commando Chicken playable character. You’ll also have the chance to earn all the Summer Sideshow achievements and unlock Steampunk Mr Foster. More information is available through the official website, and if you haven’t purchased the game yet, get it on Steam for $6.79 before November 1.