http://games.activision.com/games/wolfenstein/ click on enemy territory....free download, free play. FPS game
www.americasarmy.com also a FPS, used as a recruiting tool by the United States Army. Developed by the Army and distributed for free. Free play as well. You can download the 650 meg file from this website or go to your local recruiter and get a "free" CD containing the game. I say "free" because you will get the whole "Do you have a few minutes to talk?"
This is the best I can do for you. All free and all legal.
