So it has become clear that the final level of the tutorial is consistently bugged, as well as having (apparently) some problems with the tutorial inventory system. This is unfortunate but it should be pretty easy to fix. The good news is that I can confirm these bugs are not present in the main game.
The other major bugs I've noticed are related to a quick-and-dirty bug fix I made in the final stages of the project that lead to the red key not working properly, grenades / shurikens / explosives restocking after every screen, etc. It was a silly programming error and I will have it fixed in no time.
I will put up a new version shortly that addresses these issues, and then I'll start adding the new requested features (key binding, 2x / 3x resolutions) for a version further down the line.
Thanks everyone for the positive responses!!!