Thanks for your feedback. I really appreciate your kind words. You didn't sound harsh at all by the way.
I had changed the gravity multiple times now to get the right speed but in all went in vain, and before I realized it, I've already made most of the levels. Changing it then would break existing levels or make them too easy, so I decided to leave it as it is.
A lot of people have actually complained about using the 'spacebar' for jumping, so I may consider changing the keymapping later. If that's a big deal for you, you can alternatively use 'Z' and 'X' if you are using arrow keys for movement, or 'B' and 'N' if you are using 'WASD'.
I could easily add invisible walls around level boundaries, but I figured out that some people may struggle sometimes, and thus I didn't want to overcomplicate it by forcing them to solve it a certain way. I'm aware of level 6 and others. In fact, some levels do have invisible walls and collisions to prevent you from doing certain actions.
Sorry if the message is too long.
Take care!