Player 1 (orange) uses arrow keys and player 2(blue) uses wasd keys. Dark blue kills player 1, and dark orange can kill player 2. Red kills both. Both players can stand on top of each other. Both players need to fall to the bottom of the screen to complete the level. When one player dies, both are brought back to the beginning of the stage. Press r to restart a level.
All levels ARE indeed possible. (Tested by highly intelligent monkeys) Coding for main movements of sprites was by Griffpatch. Based on physics of Fireboy and Watergirl. You should check it out!