Good little time waster. The game is very simple and the objective is clear: Kill anything that moves. I would call this a good casual game, but it actually had me stuck for a bit when I was nearing the end and I actually had to put in effort. I have a couple of nitpicks/issues with the game, but overall it was well done.
1) The game appears to be balanced, but the difficulty curb takes a spike very early on. I suppose that's when you're supposed to die to make upgrades and purchases. It's understandable to have that setup, but around level 4, I was getting destroyed by those Rainbow ships at max health. The way they move and the preset damage they do made it impossible to avoid. I had to use the final weapon just to try and stand a chance, and even then I still got completely destroyed a couple of times.
2) Upon using my skill points, it seems there's no way to confirm the points before making it permanent. Had I known that it's a one click deal, I would have had a different setup and probably would have had an easier time.
3) The achievements/medals. It seems that the achievements ingame are blocked from view, preventing someone from knowing what they need to do to get it. I realize that they are the same ones on NG, but sometimes that's not always the case.
4) The Three Medals: The medals when dropped seem to just fly right by you, giving very little time to react sometimes. This caused a bit of frustration on my end when I had to go back through the whole level again due to missing one medal.
4a) To piggyback off this, the same sorta applies to the powerups. It seems sometimes that they're going too fast, but perhaps I was just too worried about getting hit. When the stage stops moving however, the powerups still move at the same speed, so it makes it even harder to get them when you would expect them to go slower at that point. (Made it especially hard to get them on Level 4 with the Miniboss, should you not be fast enough to do the job).
4aa) The only issues I have with the minibosses is that there's no setup on some of the things they do. The tank's barrel shot has no indication of when it fires, or no exact timer as far as I know. Level 2's mini was hard to determine when it would try to crush you. Level 3 is near impossible to tell when it will attack from the ground (you have a fraction of a second, even when it's slow) and even less time when it attacks from the air. Thankfully the damage dealt is very low. Level 4 needs to have an indicator on when you're about to "die", for those who had not ever played that game.
5) Other abilities. Getting a certain point number in Jump allows for a Double Jump. Why not add something else for the other ones? The game is very simple, very short, so it doesn't need to be over the top.
The list isn't bad. It's just nitpicks and such as I said, that would make the game a little more complete and/or issue free in my opinion. Other than those things, the game was great. Congrats on the Daily 4th, and keep up the good quality.