So to be honest I was never the biggest fan of platforms nor puzzle games, so im not the target audience for a game like this. That said, the art and characters are cute!
Played it on linux, got up to the "epsilons nightmare" bonus level. Didn't notice any glitches.
One thing I didnt like was that some buttons stay pushed while others dont. Maybe I missed it, but there didnt seem to be any indicator for which is which. Granted atm its not an issue since I obviously could figure out pretty quickly, but might be more annoying once puzzles get more complex, or timing more important.
On the "lonely mountain" level it felt like there where parts where I cheated past the proper solution by accepting I will take damage from the brambles. Might want to consider the player teleporting back to where they where or something when they take damage.
[spoiler]I.. is bird okay?[/spoiler]
Thanks for the demo, good luck with game!