Minicraft is specially designed for low end devices, so every device can play block sandbox game. It's mini, but it's full feature with multiplayer support too.
1. Walk around, dig and build in an infinite voxel world, and craft stuff from raw materials to help you along the way.
2. Multiplayer support for tens of players, via servers hosted by users.
3. Almost infinite world and a beautiful map generator.
LGPL code: https://github.com/gameabc/worldcraft