Slaves to Armok: God of Blood Chapter II: Dwarf Fortress (but almost universally known as Dwarf Fortress) is a part roguelike, part city-building freeware video game set in a high fantasy universe in which the player takes control of a group of dwarves and attempts to construct a successful and wealthy mountainhome. Along the way the player must face off with the dangers of their environment, invaders and sieges, vampires and other night creatures, and the occasional rampant megabeast, all while keeping their dwarves happy and their fortress alive. A second game mode, adventurer mode, places the player in the shoes of an adventurer as they wander the world and do battle with various creatures.

Dwarf Fortress is modeled on a complex and realistic physics engine that belies its comparatively primitive ASCII graphics. Every world is generated completely from scratch, and historical events and figures are documented and recorded as game lore, including any sapient characters the player meets on their adventures or have migrate to their fortress. The game is programmed solely by Tarn Adams, with input from his brother Zack Adams. Work began in 2002, the first alpha was released in August 2006, and development is ongoing. Tarn Adams has declared it his life's work, expecting 20 years before it is complete; development is supported solely through donations, and contributors receive either short stories or crayon drawings as thank yous from the developers.