Hi Michał!
I've played your game. It should be a liitle more dynamic, and by that i mean it should have more animations. The work of the camera is a little bit stiff, and i can't see much on the left side of my character, the camera should look more at the direction i'm going (when i'm going right, camera should be looking to the right and when i'm going left, the camera should be lookong left). You should definitely add music and more sounds. Also, you should quit using Arial font, cus it doesn't make it look too proffesional.
I've encountered one bug where i got stuck in a platform which resulted in my death.
What i like the most are the backgrounds, they are well drown, also enemies' death animations are ok .
Sincerely,
Bartłomiej
PS: Here's my game: https://xilean1.itch.io/tealground