So far I've bought a lot of Fallout games...Fallout 1, 2, Tactics, 3, and all the DLCs for New Vegas (Had the base game for awhile but only one of the story based DLCs). Great series, I highly recommend it to anyone who's into RPGs. New Vegas is the only one I've really played but I've seen the others played by other people and really look forward to getting into them.
Also got Battleblock Theater, which is pretty fun. Skyrim as well, which I haven't played much but I'm pretty sure I'll like. I think that's all I've bought so far.