Minetest is a free software game, which is very similar to Minecraft. The Tuxiversity project is running its own game server, which can be used to learn the game, and you can also collaborate with other users.

In addition using the Lua programming language you can develop you own scripts for the game.

Hopefully in time, people can run their own servers and games, which will teach some really good skills during this process.



Minetest Lua Developer reference