Ground Digger for Android

The player controls a machine, a drill for underground travel. He has to bury himself underground and extract precious stones there. The fuel supply is finite, and in order to refuel he must go up to the ground.

There, on the surface, you can improve your machine. As you improve it, it grows in size, starts digging at higher speeds, and also gets digging drones as helpers. In the course of the game you can unlock new worlds, layered on top of each other.