Thanks for all those feedback guys! The game isn't completely balanced I know, some people say it's easy if you keep your health full but I honestly don't think you can beat it this way. I personally like to keep my health low and have long dashes around. It's a tradeoff between speed and vulnerability, if you make any mistakes dashing you're dead.
The gun sure seems useless, it's supposed to be used to slow down monsters but in the end I too just use it to get slimmer and faster again. Also, it was supposed to have a boss at the end that you would beat only by making him fatter and fatter with the gun until it explodes... but I din't had time for that.
A lot of people seemed confused about the mechanics and I guess that having a little tutorial would really help things there.
The theme isn't that great either, I just draw some random stuff and then tried to make things fit together. I'm no artist. Thinking back into the theme I'd go with a magnetic armor and robotic enemies that drop scraps that get dragged by your own armor, thus, making you heavier. Your scrap gun would make them slower and you lighter, but with lower defense. Damn, why didn't I have this idea before? (I'm not even sure I'd be able to make descent artwork for that)
Anyway, up till now I don't know of anyone who could beat the game. I even offered a beer for my coworkers to whoever beat it first... I guess the hard fun I tried to achieve was just too hard for a not so attractive game ;P