GOG.com the game distribution service from the developers behind The Witcher are running a special promotion. All you have to do is head over to their website and download their Galaxy client. It’s their own version of Steam and it’s still in beta. To encourage people to download and stress test the program they are giving users a chance to claim System Shock 2 just by installing and logging in through the software.
The game is normally available for $9.99 so it’s a great deal. The promotion runs for only 2 days so grab it before it’s gone.