Awesome Game!
...but I do think defeating the doom bot should give a "you won" screen instead of looking like you died.
There are also has some balance issues, since none of the high-damage, slow-fire weapons are really viable. If anyone's having trouble beating this, just get the laser pistol, and then save up until you can get the laser chain gun (skipping the stuff in-between). There are two reasons these kinds of weapons beat all others in this game: the first is that the weapon power-ups are time-based, meaning the fireball is more effective for high-rate weapons. The other reason is that the high-damage weapons generally don't do splash damage, so any extra damage dealt after an enemy is killed gets wasted.
If you want this game to be a "10", add an good ending for defeating the boss, change the power-ups so that you have limited ammo or fire-rate, and add some extra abilities to the high-damage weapons, such as splash, slow, etc. to make them better.