THIS IS AWESOME, i like the physics for this actually, this is very ng mascot material, reminds me of gappy!, but way more simplistic (which its very good at!), the level design is great and very fun to go through, its NEVER frustrating which I TIP MY CAP TO YOU you managed to do that, its challenging but not frustrating and easy but not boring, very nice, the theming is amazing, and its very inspired and inspiring!!, honestly this just has a lot of good game design choices im not even sure i can list, for a few it has good coyote jump time, good fall speed, the arrows on the treadmills arent all flashing which would have made it very distracting, i noticed it has 2 types of levels, linear and kind of open, the linear ones are hard but it will make sure you dont miss a key while going through them, and the open ones are easier but have the keys more scattered, very nice balance, the health system is very generous which contributes to this being not frustrating, the space ship enemy actually gives you a lot of space to time your jump on him instead of being directly above your head at all times (kinda like the fishing boo in super mario world), and just good general speed for obstacles, nothing comes at you too fast or seem impossible to dodge, this was honestly delightful to play
some things i would like to add/change
-the fire balls in world 4 SOMETIMES hit me when im standing right under them, maybe they need to get a smaller hitbox or just fixed
-additional controls on keyboard!, like wasd and shift for jump (it already is just need the wasd)
-volume controls?, or a pause menu in general really
-maybe make the temporary blocks in world 4 respawnable, i mean i dont think you need them that much but it would still be nice i think
-i know its pretty short but a save function and level select would still be nice
thats all i think, this was very charming to play through, thanks for making such a great game :)