Unobtainium

The deeper you go, the more rewards you reap. Dig down, find minerals, sell them, upgrade your rig, and delve deeper still.

Look for the Unobtainium crystal down in the bowels of the earth. Beware, far underground it is difficult to see. Luckily, you have a flashlight - one that costs far too much energy to operate, though...

This is a game made in under 48 hours, during the 39th Ludum Dare competition. It's based on the theme 'running out of power', and heavily inspired by a certain Flash game that is infamous for fuel tank troubles.