Fans of science and cake, rejoice! Portal: Prelude, an unofficial and completely free Portal prequel mod, reveals the innerworkings of Aperture Science in the days before GlaDOS - when human employees administered all of the tests. Sound intriguing? Since it's a mod and not a standalone game, it requires both Steam and the full Portal PC edition. If you meet the system requirements, download it now. What do you have to lose beyond a few gigs of hard drive space? For the record, there is reportedly an official Valve Portal prequel in the works plus a sort of story-less map pack expansion of the original called Portal: Still Alive for Xbox Live Arcade. But they're not here yet, and this is...
