some explanations would be nice
It's playable, but several questions and problems present themselves.
First question: who are these people? You never learn anyone's name, not even your "hero" who is shown at first to be quite muscular, but is apparently the size of a small child.
Second question: How the hell am I supposed to solve that puzzle? A quick mention of how to even interact with the thing would have been nice. Since you didn't give any information on that, I will. The puzzles are controlled by the arrow keys and the a button, highlight the square you want to move and press a to rotate it. All pieces must be used and you can rotate any piece that is not light grey, including the end points.
First problem: Why can't I run and shoot when I can jump and shoot? I can't find an explanation for this, other than that you could not make an animation of him shooting and running at the same time, which I find disappointing.
Second problem: In order to shoot in the opposite direction, you must stop running, wait a second, and then press the arrow for the direction you want to face. I found this very frustrating when dealing with the second boss, since I had to jump and then change directions quickly.
Third problem: Random invincibility for the bosses. The hairball was invulnerable if you couldn't see all of him, the alien pilot was invulnerable while shooting the larger cannon at you, and the final boss was completely invulnerable except for a few seconds after a tedious session of "dodge the two predictable attacks".
Fourth problem: There is no damage notice on the bosses. I had to watch the healthbars carefully to see if my attack was missing or hitting since there was no sound effect or visual effect to tell me. I found this most prevalent when fighting the alien pilot and the flying form of the guy in black (right after the jetpack upgrade).
Final problem: there is no explanation as to why you fire so slowly. You fire a round and have to wait for a while before you can fire again, despite the fact that there is no visual reason for doing so. Also, if you fire while on the ground, then jump and attempt to fire again, even if you waited out the "reload" time while in midair, you cannot fire until you hit the ground and finish the "reload" time there. I found this very frustrating in general until I got the jetpack...for the whole two minutes I got to use it.
It's not a bad game, but it's certainly not front page material. Polish it up, work on the graphics and code, and it might be a cool game, but for now it seems like a trial version of some better game. Keep working on it.