This game has a really charming atmosphere! The 2D/3D combo works well, and I really like the aesthetic. The music and SFX work well to support the vibe too. I appreciated that you included a transformation sequence, nice!
The story seems interesting, but is fairly light currently. The gameplay falls into as similar state. Collecting the cats was fine, but I found myself often trial-and-erroring my way through the puzzles. There were a few I got by looking at the pictures, but many I wasn't really sure about. Brute forcing ultimately worked.
I do have to say though, even if the gameplay and story were light, the atmosphere you've created kept me going! Pretty sure i found everything (you mentioned a cat is currently missing, so you can't win right now)
One small bug I found was that I started playing with the arrow keys instead of WASD... it works, but the character doesn't animate if you play that way. Of course, using the WASD as the instructions tell you to, the animations are fine. (Not sure why I went straight to the arrow keys, habit I guess!)
Also, I did have to restart once because I actually went the wrong direction the first time (away from the path) and got very, very lost! I suppose I should have followed the path, but maybe some sort of boundary to the play area would help for silly players like me who wander.
Great work!