Great game, just finished it.
I found a bug that made the game extremely easy for me: invulnerability.
So, I used the Shield power twice in a row(without waiting the first to end) by mistake and it bugged out making the temporary invulnerability not temporary anymore. I don't know if that bug can be repeated by the same method, but still, just had to describe how the bug happened to help you fix it.
Still, a great game and will give it another try later without using the Shield power.
Btw, there was also this, but I wonder if it's because I'm using an emulator (or an emulator on Linux):
However, this time I was not able to repeat that bug.