We're fast-approaching the celebration of gluttony and cheap costuming that is Halloween, wherein we scare ghosts and demons back into the spirit world by dressing up like political figures and scantily clad nurses. Left 4 Dead 2 is a little on the spooky side, so Valve is letting you trick your treats with a free weekend of the game.

The free period begins on Thursday, with the whole game available to try out. You can begin pre-loading the game now, if you want to jump on the opportunity. For you old hands at L4D2, it also includes a new achievement to chase. The "Good Guy Nick" achievement rewards you for helping a free weekend player survive a campaign. You'll just have to suppress your frustration when they keep shining their flashlight straight at the Witch.