Needs a lot of polish..
It's a good start for a side-scrolling shooter, but it needs a lot of work.
- The controls of the character need to be tighter. It feels and looks like the UFO is sliding on ice.
- You need to have a way to hit grounded enemies. Going to the ground to shoot just means eating missiles to the face.
- You need a life system in place. Dying just looses points, and let's be honest, we don't really care about them with Infinite lives.
- An upgrade screen between rounds would be nice, giving us options to work with like Heath, Energy, and Weapon upgrades. You could replace points with $ to make it work.
- On that same note, remove the healing when you kill an enemy, and make them drop health power-ups instead, and throw a full heal on the upgrade screen.
- The music works, but is incredibly repetitive, mixing up the tracks would help.
That's about it from the top of my head. If you work at it, this could become a good game.