Via the strange magics of download service Gametap, the original STALKER: Shadow of Chernobyl (not its deflating sequel Clear Sky) can now be played for precisely zero pennies. No region restriction (apparently), and it joins a freebie roster that also contains the stalwart likes of Deus Ex, Hitman: Blood Money, Psychonauts and - yes! - Hotdog King.
The twin sacrifices necessary to gain this gratis copy of one of the most original and atmospheric FPSes of recent years are 1) installing Gametap's adverty download app all over your PC and 2) Gametap's despotic encryption system ridding you of the ability to mod STALKER in any way. While the vanilla game is many splendids, the huge modding scene improves it exactly thirteenfold. I guess you could consider the Gametap version the demo, and buy a non-nerfed copy elsewhere if you like it. Where? Here.
Edit - 64bit Windowses are not supported, by the sound of things.
Edit edity Mcedit - sounds like this may only be the case until the end of this week. Get your blinkin' skates on. Seems savegames will be transferable from Gametap's paranoiaware version over to the standard version, at least.