Angband is based on the world created by J.R.R. Tolkien (Angband being the fortress of Morgoth, the ultimate evil guy). The player has to crawl down the 100 randomly generated levels of a dungeon in order to defeat Morgoth.
Versions and platforms
Angband is open source. Being a major roguelike, it is available under virtually every platform. Latest version is v. 3.0.5, dating from May 23, 2004.
The clean and modular source code of Angband made it a good start to create a roguelike. As a consequence, around sixty variants of Angband have been released. Some of them, like ToME or Zangband, became as widely played as the original.