Nice little platformer here. I am having fun here. I also found the mechanics where you transform into a ferret interesting, but it just feels like it's not that well used and didn't distinguish itself with the normal character. There are one jump that is a bit too tight in level 2, but other than that the levels are solid. Need to utilise the tiles sets a bit more though, get a bit more personalities or even tell a story with them. Also some visual cues for the wall that the ferret can pass through will be nice.
Anyway, keep on the good work!