You're making some interesting games, but they always have one in common unfortunately.
They are faulty.
Here are a list of bugs, that I've found.
1) Rocket-Jump Glitch
You grab the "missile" power-up in an idle state. After getting the missile, hold the jump button.
2) No enemy spawn glitch
I have no idea how to trigger that, but it happens occasionally.
3) Fireball of Death glitch
Firing multiple fireballs causes the screen to freeze.
They are kinda game-breaking and I don't know, if you can fix this or not.
Now for some compliments.
I really like the idea. The game itself is enjoyable, the music is entertaining and the graphics were pleasing. This game has room for more ideas, so I would totally welcome a sequel to this.
The character choices were nice, but one of the last two were a bit disappointing. One of them was barely playable, because the jumping seemed awkward. I still have to unlock the very last one in order to give my full verdict.
I hope this lengthy review will help you.
In short, your game has some bugs, but I liked it anyway.