Disgaea 3 platinum. The ladies are always impressed.
Also, bizarrely, Guitar Hero. I put an incredible amount of time into the first game over one summer in my quest to 5 golden star every expert song and I ended up becoming a beast in the rhythm genre in general, I found the payoff from nailing those really hard songs to be very satisfying and still even now I get the itch to play one from time to time.
Post edited May 03, 2013 by Goatbrush