
I stumbled upon Desktop Dungeons while being bored one night, and boy did I become addicted to this fast! It's basically a stripped down version of Rogue, obviously using actual graphics, that has been designed to be played in less than 10 minutes. Sounds stupid, until you're saying "just one more go" at 4am before work.
I recommend it to any fans of the genre: plenty of options, unlockables and loads of charm.
Get it here.