Dig underground to collect all crystals spread across the deep earth. Use your left and right arrows to move, up key to jump and hold the appropriate arrow key and space to destroy stone to get you where you need to go. Watch your stamina though, because if you run out before you hit the exit you will have to restart a level. There are 20 challenging levels waiting for you! Get all the crystals to go through the door to the next level. Have a delightful time playing Hidden Crystals Of Deep Earth!