Hoary old gamers (read: anyone around since The Orange Box) may recall that it shipped with Peggle Extreme, a standalone Half-Life-themed bundle of levels for casual megahit Peggle. If you’ve ever been curious but haven’t wanted to shell out the cash, Valve is now offering it for free via Steam. For those unfamiliar, Peggle is a gravity-driven puzzle game where the objective is to destroy every peg on a game board by bouncing a ball among them. It’s sort of like pinball without flippers, and has a habit of depriving otherwise productive members of society of their duly-earned sleep. Go have a crack at it.