Dungeon Crawl Stone Soup is a free roguelike game of exploration and treasure-hunting in dungeons filled with dangerous and unfriendly monsters in a quest for the mystifyingly fabulous Orb of Zot.
Dungeon Crawl Stone Soup has diverse species and many different character backgrounds to choose from, deep tactical game-play, sophisticated magic, religion and skill systems, and a grand variety of monsters to fight and run from, making each game unique and challenging. Dungeon Crawl Stone Soup can be played offline, or online on a public telnet/ssh server thanks to the good folks at crawl.akrasiac.org (CAO) and crawl.develz.org (CDO). These public servers allow you to meet other players' ghosts, watch other people playing, and, in general, have a blast!
Dungeon Crawl Stone Soup has an active community with a lot of discussion in ##crawl on Freenode IRC, on the crawl-ref-discuss mailing-list at SourceForge, and on popular Web forums such as Game Spite, Bay 12 Games and Something Awful.