Minetest
Minetest is a free and open source voxel-based game engine, which uses the Irrlicht rendering engine. The game engine comes with a default game, named "minetest-game", but also allows for the use of other games referred to as sub-games. Minetest was designed around some of the concepts used in Minecraft and InfiniMiner. It borrows many concepts from Minecraft, such as "crafting recipes" and the overall mechanics of the game. However, it differs from both games in that it is an engine rather than a standalone game.
Installation
Minetest can be installed from minetest or minetest-gitAUR.
A dedicated server package for the game engine is provided in minetest-server.