This is a really clever idea for the theme, I think I enjoyed the run speed increase from being small far too much as a lot of the time I missed my jumped by not being able to control the speed!! This is great, really well made!
I did have an issue on my first attempt to play, where the spring at the start seemed to bug out, and after I scaled back up in size to jump on it, I ended up somewhat stuck in the floor? And wasn't able to jump at all from then on. Didn't happen when I restarted and tried again, but thought I'd mention it for you!