Cool concept, good presentation, level design was good too. I encountered some bugs with the checkpoint system and in particular had to give up when I got stuck in this state: https://i.imgur.com/y4HlX05.png
But yeah, I like how the spring is simple enough to predict the behavior of and how it works both in compression and extension which lets you use it in creative ways.
The control scheme was a bit difficult to internalize but the characters weren’t too difficult to control once I got used to it, so maybe they’re fine as they are, but there could be some room for improvement there. Like you could for instance experiment with controlling both simultaneously.
Oh, and one thing that confused me is that I’m still not sure what surfaces I can stick to and which ones I can’t – it seemed kind of unpredictable since sometimes I could stick to walls and other times I could not. It even let me stick to the air sometimes.