As Portal comes to its first anniversary today, the one of the first full mods for the game releases in its full glory. Portal: Prelude puts players into the pre-GlaDOS era of Aperture Science where real scientists did the dirty work, not that cake-promising machine. This story has great potential, so great in fact the Valve announced back in June 2008 that they were working on a prelude to Portal themselves, but the man behind the mod, Nicolas “NykO18″ Grevet, continued to create and now release his vision of the game.

Update: Download links are now available at Filefront, Fileshack, Mininova (torrent), and more.

FilePlanet managed to get 24-hour exclusivity rights from Grevet (a bad decision in my opinion, mods should be free to everyone at all times), and the mod is set for release to the general public tomorrow. You can watch the trailer below for the mod while the 775 MB gets onto your computer. If you are unsure of how to get a mod properly working on Steam, Planet Half-Life has a tutorial on installing mods.

Get the Flash Player to see this content.

Youtube Link