Use W/S or arrow keys to move up and down. Once you collect the ninja stars (by touching the green boxes), fire using the space key. Once per game, detonate the bomb by pressing B. It destroys every enemy on the screen. Once you collect the shield (blue box), you can use it for 6 seconds by pressing the I key.
This is CRAZILY, INCREDIBLY, SUPER ULTRA MEGA laggy on every computer I've played it on, so be ready. It kind of makes the sprites look weird when it goes superslow.
