Thank you for the detailed feedback!
The difference in air control while running was intentional. I wanted both running and not running to be important choices for the player. However, it may not have been the best decision for a precision platformer.
My goal was to make the movement feel unique, like something you have to learn and understand rather than instantly master. Still, I'll definitely take another look at it in future updates and see what can be improved.
I'm really glad you enjoyed the game. Thanks for playing!