Inspired by Rogue, NetHack is an ASCII-based RPG in which the player must navigate the Mazes of Menace in search of the Amulet of Yendor for his deity.
http://macmost.com/e-782 Classic role playing games from the 80s and 90s can still be played on brand new Macs running Mountain Lion. Take a look at NetHack and Ultima IV, two of the all-time best. They are both available for free. Another classic, Baulderapos;s Gate, will be coming out later this month.