I liked the game and had fun with it, the graphic are pretty nice for this style of game, Upgrade system so simple but works. but there also smalls things...
Sometimes i just feel this game is more "Luck based" rather to "skill based" some levels get pretty easy due this, but how is "luck based?" easy sometimes you get stronger enemies before you touch your health potion, food etc. so you get killed in the end, but sometimes you get stars even twices after one ending which make some levels easier. so sometimes upgrades doesnt matter. (i got full upgraded before the sky palace).
Maybe you can make in the next version a "upgrade to make appear a bit more often the stars?" like a Luck upgrade
desert was kinda nice due the mirage while i understand that game need to be "challenging" i feel a bit "unfair" for the player when you get "after a wall of enemies" a food but in the end was a mirage and then you get killed due you was a bit confident about you will restored a bit your health, i dont mean to remove mirages, but maybe you want to make a bit "different" the food mirage from the normal food, not a lot different but something that the "skilled" eye of a player can identify and make sometimes them to confuse them for normal food. this add a fair chanllege from the players side.
there also a small thing that maybe is just me but when i have the chance to take 2 stars one after i got the previous one like 3 segs before, the "new start" dont make last longer the effect from the previous start, its like i never got the second start, usually when you get the "second" power up like this kind of power up its make last a bit longer the effect. just telling.
Anyway, the game is great is fun i usually dont like the "keep moving games" but this one really got me just sometimes make feel that the game is more based on luck rather in your luck or your power ups (because even full powered up make you feel you still need more).
anyways good work and keep it up!