- The price is too high for what you get. Judging from the reviews, it only has about 3 hours worth of gameplay.
- Header art is bad. Don't use AI, or at the least, try to make it look decent and not have the brownish-yellow AI tint. Even a screenshot of the end of the trailer would look better. It gives a bad impression.
- Unclear what the gameplay actually is. The Steam description alludes to "secrets" and "mysteries" in the game, but the trailer and images don't show anything other than flying and building up the little hub world place, so it seems like the description is trying to overstate what the game actually is.
- Small/niche audience regardless. It seems like it's meant to be a purely relaxing game with no story, enemies, major obstacles, etc. That already limits your audience quite a bit.
- Smaller nitpick: the crystal collection UI looks terrible. It's just a png and default arial text. Change that, it's an easy fix.
TLDR: Replace the header art (and based off a review, the in-game paintings if they're also AI), lower the price, clean up the Steam description, fix that UI, and if it's feasible, add more gameplay.
For gameplay, adding a mode upon completion where you fly infinitely (that just loops through the maps or plays them in random order) to see how far or how long you make it until you crash would probably be less expensive than outright new content. More and better collectibles is an easy one. No customizing or altering the kite is a HUGE missed opportunity.