Buildcraft is an infinite-world block sandbox game. Buildcraft with its truly multi-player feature, you can create world as you like.
Interactive tutorial for new hands, lead to learn how to build and craft!
Beautiful multiplayer servers !
Walk around, dig and build in an infinite voxel world, and craft stuff from raw materials to help you along the way;
Simplistic Modding API that supports many kinds of additions and modifications to the game;
Multiplayer support for tens of players, via servers or local WIFI;
Voxel based lighting with gameplay consequences (light caves and buildings with torches);
Almost infinite world and a beautiful map generator.