Dwarf Fortress is a single-player fantasy game. You can control a dwarven outpost or an adventurer in a randomly generated, persistent world. The world is randomly generated with distinct civilizations spanning over 1000 years of detailed history, dozens of towns, hundreds of caves and regions with various wildlife. Command your dwarves as they search for wealth in the mountain. Play an adventurer and explore, quest for glory or seek vengeance. Extended ASCII character set rendered in 16 colors (including black) as well as 8 background colors (including black). Although Dwarf Fortress is still in a work in progress, many features have already been implemented. Please post all support issues in the forums for the game.
Here's an underground lake with some giant fungus growing nearby. The green marks at the top are "memory map" markings of some giant cave spider cobwebs he passed by on the way to the shore.