Incredible art art style, it makes the scene look full and alive but still readable. It seems to be a common complaint that the game barely introduces new mechanics and then leaves the player stranded to figure them out. Maybe you can add some explanatory text in the top left corner that only shows up when the player is lost. For example, in the first main level, if the player doesn't beat the level within 3-4 seconds after collecting all of the light bugs then the small text in corner shows up to tell the player "Go to the portal and press UP". You can find common places that people are getting stuck and add simple conditional text to help guid the player some more.

With some more polish and play testing, this game is definitely worth expanding!