Thank you very much for the detailled explanation! This is perfectly valid and makes sense. I should have made at least a minimal intro screen, maybe in-level, to show the goal of the game and explain the elements you can see, at least a little. I'll keep that in mind, thank you :)
I was also not sure on how to handle the How To. Having it open in each level might be annoying, but on the other hand, players might miss it - and its content changes from level to level, depending on what i thought was relevant. I have to think about that :D