I've been installing Steam in various versions of "Ubuntu-ish" Linux distros, and it works great in Linux Mint 14 MATE. I'm using an older nVidia GeForce 9600GSO. The official Launcher does not work, of course -- you have to go to your Home folder, hit CTRL+H to view hidden folders, then go to .steam/steam/SteamApps/common/Amnesia The Dark Descent/ and then double-click "run_steam.sh". I've tried making all sorts of links to the desktop to make running easier, but no launcher seems to work -- I just used a link to get to the Amnesia folder. Awesome game!