12-18-2014, 02:18 AM
I have no idea if that would break the EULA, it will most likely be a copyright infringement (unless we limited it to be only a multiplayer client, and even then it's a shady area) and it's so much work that it's highly unlikely to be attempted. There are a few projects that tried to clone minecraft, most of them are not doing too well. One notable exception is MineTest, for some reason it seems to survive Using MineTest as the basis for a client is a much more viable way than creating something from scratch.
Ref.: http://minetest.net/
Ref.: http://minetest.net/