I agree the lack of player-onboarding is a real problem, you kind of just get thrown into things. There are tool tips in the key binding screen from the start menu but I doubt most players will ever see that, it would have been better to add them to the game screen as well so that you can hover over the buttons and know what they do. Glad you were able to figure things out on your own!
Noooo sorry about the R thing lol, I had that in as a temporary thing when playtesting and forgot to take it out (woopsie). Very nice to hear you liked the main menu sounds, I wasted a lot of time on that instead of more important things (like a tutorial lol).
There were a few bugs related to the bug (no pun intended) that made the screen go black occasionally in my playthroughs so its likely something along those lines. If I put more work into this game I'll certainly have to squash that.
Thank you very much for feedback and the kind words!!