All right. Let's start off by saying that the ambience - the sounds, music, etc. - are really neat and made the game come together as more than just a clone of Space Invaders. Good job!
However, I have some suggestions for improvements.
- Make it so that either you don't have to download a certain package to play this game, or make it clear that you have to download it and give a link to where you can download it.
- I think you should have a sort of "Powerup" system where if you kill a certain number of aliens, than you can obtain something like a better laser gun that shoots a larger laser bullet, or has less cooldown for shooting. Or maybe more health. Anything that rewards you something other than a high score for skill.
- The current cooldown for the laser gun is too slow to kill all the aliens in some levels, as not being able to do so can be frustrating when you know it's not your fault and it's instead the game's. Maybe, as a fix, you could not have aliens that go off screen, or make it so that you can get enough powerups for your laser to have a cooldown that enables killing all the aliens that go offscreen.
And that's it! I hope my feedback lets you improve your game and make it better than before!
-HoneyFun