Terasology is an open source game based on the Minecraft-inspired voxel world. It is a modern, open source, and extensible voxel-based game engine. The goal of the project is to create a voxel-based game engine that allows for user-created content, including modding, scripting, and even entire game modes. Terasology also offers an intuitive user interface, as well as a wide variety of game modes, including survival, creative, and puzzle-based. In addition, Terasology comes with a powerful scripting language, allowing for custom game logic to be implemented. The game engine also supports a range of additional features, such as procedural terrain generation, custom textures, and complex particle systems. Terasology is a great way to create your own voxel-based game or just to have fun exploring the world of voxels.
Discontinued announced in IRC chat: http://irc.minetest.net/minetest-dev/2017-07-17#i_5011943
Discontinued The latest version is more than 6 years old. See http://mythruna.com/download-now/20120627-release-notes/