WolkenWelten is described as 'Multiplayer Voxel Survival in C99, includes a badly written implementation of LISP' and is an game in the games category. There are more than 10 games similar to WolkenWelten for a variety of platforms, including Windows, Linux, Mac, Android and BSD apps. The best WolkenWelten alternative is Minecraft. It's not free, so if you're looking for a free alternative, you could try Luanti (formerly Minetest) or Veloren. Other WolkenWelten like games are VoxeLibre (formerly MineClone2), Terasology, STALCRAFT: X and Infiniminer.
MineDroid is a viewer / concept design for Minecraft that supports using your own 1.3 beta levels, temporarily building and destroying blocks, sensor steering, crouch jump, ghost mode / fly mode. more features to come, you can get the source and help out...
