IHMO Adom is the best one you can run from the command line.
Tons of spells, item, quest, skills, mosters etc and quite realistic (for example you can freeze water and make yourself a bridge; your potions can explode when its to hot etc

). The bad part is the controls are hard to learn and it can get heavy on the CPU if there're to many mosters in one place (100-400 MHz pre game).
Runs on *nix and M$ (in dos window)
http://www.adom.de