Ubisoft has officially released the Far Cry single-player demo, available as a gigantic 496mb download. The demo features one mission called Fort, and has seven weapons from the game available. To run it you'll need at least a 1Ghz machine with 256mb of RAM available, though 2Ghz and 512mb is recommended.

[ Download the demo ] You can find out more about this game by going to the official website.