UFO is an enemy in Kid Chameleon.
The UFO is a cute little spaceship with a gross spidery thing at the helm. Its usual behavior is to fly around at high speed, looking for someone who looks like they need a few gigawatts of space alien ray juice dumped on them. It can see you from an infuriating altitude (even way off screen), and when it does, it gets above you and starts firing and just doesn't stop. If the UFO is too high for you to do anything about, you can always try running back and forth in the hopes that it'll give chase and come down a little lower. Once it does, all it takes is 3 hits, one for the cockpit glass, one to destroy the ship, and one for the alien pilot that falls out.