it was good, i feel like the player could have been given more visceral reward for climbing higher, e.g. areas with different appearances, some more interesting UI for the distance you have climbed, my idea is you have a scrolling, mostly transparent map that looks similar to the compass UI in a lot of games that pinpoints your location, highscore, and indicates good places to reach e.g. the start of those biomes, other rewards, etc.
At first i read 'background music' and thought, what music? and it turns out that the music starts muted despite not being according to the icon. it was suitable for your game though, if you were willing to put extra into that biome idea to really spruce things up a bit you could add slight variations to the music per biome: take Celeste's track 'reach for the summit' as inspiration, just probably not quite a strong of an effect as in celeste.
As for 'game feel' i thought it was pretty good; just mess about with the camera, particles, movement, see what works. at one point however, i died because i saw the top of a boost arrow and for whatever reason decided it would probably bounce me even though the actual platform was offscreen - make of that what you will
As for new ideas, possibly dot little surprises occasionally to make the player want to explore: just a theoretical idea and i have no idea if its a good one but if there was to be any sort of shop - perhaps it would not be housed in the menu but somewhere on the infinity-cave-tube-mountain-thingy, probably only a short distance up.
Overall, i enjoyed it and have followed your itch account: i look forward to your next move.
I'll probably post something similar to this for my own game so stay tuned - if you want to give feedback rn you can find it here: