Here are a couple:
A classic game is "rogue", the first 'dungeon crawler', text based.
(I went to get the link for you and played a game, man it was a great game going, I had most scrolls identified, banded armor plus enchants, a two-handed sword plus enchants, even a scare monster scroll waiting, and I underestimated a troll and clicked fast and got killed in what seemed like three hits, crap, was a really good game going).
http://www.play.vg/games/87-Rogue.html
For an old style RPG, the current Humble Indie has the latest Spiderweb Software RPG for about $5 for the package.
There are now a ton of 'free to play' games that are good but you are limited if you don't pay. LOTR, D&D, AoE, and many more.