Desktop Dungeons is a ridiculously addicting dungeon crawler, simplified so that each game takes about 5-15 minutes. I've been playing this game 3 hours at a time; seriously, it's well made.
http://www.qcfdesign.com/?cat=20
I recommend switching to the "fegon" tileset when you start. It's much better than the default, in my opinion.
It took ages for me to get my gamertag linked, because EA site bugged for me. I finally got it to work not so long ago, and am finally able to see screenshots I've taken. And those were taken by accident, when I didn't know how to take 'em (only noticed the feature when "achievement unlocked" popped on my screen, for unlocking the one that you get from taking 3 screenshots). So they are mostly just closeups of ground, with couple knifekills