The object of the game is to drill your way down to the end of each level without running out of oxygen. There are soft rocks that you can drill through very easily and there are hard rocks that take up to 20% of your oxygen to break. Both Soft Rocks and Hard Rocks can fall on you and kill you. You can pick up oxygen bottles on your way down to top up your oxygen tank. The levels become longer and more difficuilt as you drill further down.