The P U N K is walking around in a labyrinth where green doors try to stop him. Fortunately he can fire a laser beam at the locks that can open the doors. These are white cubes, that he can fill with his red laser beam until they're completely red. You can also use mirrors, when a lock is out of reach. Be careful not to hit the P U N K with his own laser beam that's reflected by the mirrors: it will kill him!
Use the arrow keys or WAD to move. Press the spacebar, the up arrow or W to jump. if you want to jump higher, press one of these keys twice. Click to fire and hold the left mouse button when you want to fire a long beam.