Just in case you want to know exactly how it plays. When playing, the first level is just avoiding the red missiles from the UFO, the second level is kicking/hitting the monster heads before they burn up the structures at the top. The last level is timing a shot from one side to the other to hit the big monster. The 'laser' (whatever it is) flickers to give it a shimmering effect.
The first two levels are timed from what I can tell, you just play for a minute or 2, the last level you have 3 shots, and then it starts over.
Since it's just demo mode, lives and score aren't used.