Angband
Angband is a freeware, open-source computer game of dungeon exploration, based very loosely on the works of J.R.R. Tolkien. You explore a very deep dungeon, kill monsters, try to equip yourself with the best weapons and armor you can find. The goal of the game is to defeat Morgoth.
Official website for Angband is angband.github.io.
Angband is primarily text based, although graphical add-ons (tile sets) exist. See some screenshots to get the idea. The live game can look like this.
Angband has a very long history. It started in 1990 as an improved and "Tolkienized" variant of Moria. Moria itself was created in 1985 and was inspired by Rogue (from the late 70s). The first version of Angband was created by Alex Cutler and Andy Astrand at the University of Warwick. The notable maintainers in the 90s were Charles Swiger and Ben Harrison. In 2000, Robert Ruhlmann took over. Starting March 2006, the game was looked after by Julian Lighton, and since April 2007 by Andrew Sidwell. Starting the release of 3.5.0 on Christmas Day 2013, the game is maintained by Nick.
Angband is a member of a family of similar games called rogue-likes. Other well known games of this type are Nethack, Slash'Em or ADOM.
Angband, with its source code available to general public, spun a lot of variants over time - versions of the game with changes against the original Angband. The original Angband game is referred to as Vanilla Angband.
Angband is dual licensed, either under the historical Moria license, or under GPLv2.