Escape from your cell with the help of a magical gun, that makes temporary holes in walls. There where you see a green square with an arrow inside, you'll be launched in the direction that the arrow points at when you enter the wall at that spot. You can walk both aboveground and underground. Alternate both sides in a smart way, so that you can get further: sometimes you get stuck aboveground, and you can still continue underground.
Use A and D to walk and W to jump. While using your magic gun, use the mouse to aim and to shoot. If you hold the left mouse button, you create an opening in walls that normally you wouldn't be able to climb or break through. If you want to alternate the aboveground and underground world, you do so by clicking there where you want to go. When you get stuck in a level, you can press R to restart. Use Q to go back to the main menu.