Minetest is most of this : http://minetest.net/ http://minetest.net/ The flat game is a voxel engine that does mostly what MC does. It is written in C++ and is

Minetest is most of this : http://minetest.net/ http://minetest.net/ The flat game is a voxel engine that does mostly what MC does. It is written in C++ and is a billion years more optimized than the desktop Java Minecraft client. It is also open source. It has an actual modding API, and has a bunch of mods like mobs and home decorations, etc, but nothing on the scale of the Minecraft mod scene (which is kind of insanely stupid, since you have to decompile the Java binaries of MC to mod it at all). I do think the Minecraft mod scene is at its own dead end. Mojang iterates slowly on the game if at all, and its proprietary nature prevents true collaboration. It is a real shame all the effort is being poured into Minecraft at this point.