Angband is a role-playing game. Light on graphics (all features are represented through ASCII characters (numbers, letters, etc) and heavy on gameplay, it's based (loosely) on Tolkiens work. screenshot of Gumband
Me facing some uruk-hai. The equipment screen and monster information and messages screen below the main gameplay screen, and then the inventory to the right.
Click to zoom.
For instance, the player is represented by "@", trolls are "T", orcs are "o" and so on. Open doors are "'" and closed ones are "+".
The aim is to collect some suitable equipment, and venture deep into the dungeon, before facing Morgoth at the bottom of the dungeon. The lower you go, the better the equipment you find, and the tougher the monsters you face. You only have one life - once you die, that's it, you have to start from the top again. Angband is a *tough* game, and it frequently takes years to complete.
Because Angband is open source, and written in very well commented C, it has spawned many variants. My favourite is Gumband, which is based on Michael Moorcock's "Eternal Champion" Saga. Patch

I've written a patch for
ToME, you can
find more about it here. I've also written the in-game lua help files for ToME

Links

Thangorodrim
Variants
Gumband
ToME
Everything
angband.oook.cz