Algodoo

Control the purple/left one with W to go the direction of the red, S to go in the direction of the Blue, Q to rotate counter-clockwise, E to rotate clockwise
Control the green/right one with I to go in the direction of the red, K to go in the direction of the blue, U to rotate counter-clockwise, and O to rotate clockwise. The goal is to kill the other person. The red spike can kill them, however it can be blocked by either colors. If two reds collide, both sides will lose their red. The blue will block the red without destroying it, and also throw the other person far away.