Dungeon Crawl is
awesome.
Incursion tries to use Dungeons and Dragons rules (3rd edition), and it seems to work. It has very nice dungeons. You have to actually sleep to regain hitpoints or spellpoints, but thankfully you can camp together with the other adventurers.
There are lots of spells and lots of feats and lots of choices, which makes character generation quite complicated.
DoomRL is pretty good, especially with the sounds on. It's Doom 1 as a roguelike, with Doom1 music/sounds, random levels and blood spatters and explosions and lots of fun stuff.
Dwarf Fortress is absurdly complicated, and awesome in its complexity. I haven't played it for a while, because there aren't any actual gameplay goals in it ATM, but I still read about
the new stuff.
"Today was compound fractures as well as fractured layers being knocked inward to damage soft inner portions. So a bone in the arm for example could break through the skin if the arm is struck." It's awesome to read, even though I don't actually play the game. I mean, roguelike with an animated ocean, and waves? Trees turning yellow in autumn and dropping their leaves for winter? Bushfires?