Seeing as comments turning into a list of roguelikes:
ADOM is one of the best roguelikes. It's closed source but very deep and high quality.
http://adom.de/
POWDER is a little graphical roguelike targetted at portable game consoles and PDAs. But you can play it from PC. It's reasonably quick and have a very fun and orthogonal skill/spell/item system.
http://www.zincland.com/powder/index.php?pagename=release
TOME (http://www.te4.org) is ADOM-ish (reputedly, haven't seriously played ADOM) and pretty fun. I found the level generation a bit repetitive, though.
ADOM is one of the best roguelikes. It's closed source but very deep and high quality. http://adom.de/
POWDER is a little graphical roguelike targetted at portable game consoles and PDAs. But you can play it from PC. It's reasonably quick and have a very fun and orthogonal skill/spell/item system. http://www.zincland.com/powder/index.php?pagename=release