This was a bug that happened on some Windows machines. I just uploaded a new version that should fix the issue. Could you try again? Thanks! :)
I will thanks!
It works fine now, but, now I can't jump anymore, I've tried to change the keybind to something else and I've tried to restart the game, but, I still can't jump.
Jumping is an upgrade... :D You unlock it by collecting green shards and then upgrading (you'll see).
Oh okay thank you!