Hey, thank you for your detailed review!
Let me address the points you mentioned here:
First and foremost, they are all valid and I would address them with fixes, if I could.
The level select was a must for us, because it made testing easier. The softlocks where intended and originally you should be able to restart the game there, but due to time pressure, we decided that "going into the menu and select the level again" was a compromise that was fine.
Same goes for the controls: We thought about adding them in, but because of time constraints we put them into the readme. Now they are available on the game page, the readme and the GitHub readme. I would add them in, but because of the voting phase, the game is locked.
I never tried alt+tab... I should do that more often when testing games. But to be fair: The fullscreenmode was added like half an hour before submitting, it was originally just windowed. Also if that bothers you: You can make the game windowed and change the resolution, by editing the config file that is created when starting the game for the first time.
But overall, we are very glad that you enjoyed the game!