Really happy to hear that you liked the game! Haha, don't worry about the previous versions - 1.1.0 (and maybe higher later) is the one that you want to play!
It's great that you found 3 power-ups! There's currently a total of 4 in the game, so keep trying! I actually planned 6 more on top of the 4; 2 of them are actually in the game, but I disabled it for balancing reasons. D: The remaining 4 included a wall-destroying ability and the ability to fly, but I didn't have enough time, and the current levels didn't really necessitate the abilities. :( The attacks were weird things to change during the jam. In the previous versions, the fireball actually had a lower firing rate but did more damage. I realized that people were having trouble using it, so I sped up both the normal and fireball attacks, but reduced the latter's damage. I guess that kinda led to it feeling like a redundant attack. DX
Yeah, the double attack's a weird bug! In fact, if you hold down the attack button while you're falling, you can also do a double shot. XDD