Not entirely sure if you just want old school text games, or if you're looking for text games at all, but I'll jump in.
Go to Baf's Guide To Interactive Fiction:
http://www.wurb.com/if/index
Get yerself z-machine interpreter for your machine (I use WinFrotz for my Windows box), and then download some games. Adventure has been ported to the z-machine numerous times, but there are plenty of great new games. Some recommendations of mine would be: Anchorhead, Christminster, and Jigsaw.