Thanks for the feedback :)
1) Increased the movement speed, but initially the speed had to be collected with coins. Removed this ability from the coins and now they are useless.
2) In the camera, I made scaling on the mouse wheel. But for some reason in the web version the mouse wheel behaves incorrectly. I also understood what you are talking about. Such cameras were implemented in early 2D games.
3) Used ready-made assets.
4) I watched a video of the walkthrough of Mole Mania on the Gameboy. A very interesting game, thanks for the tip :)