Would pay for this. With some minor changes I'd definitely enjoy this game as a mobile app because of the nature of the gameplay. When you're climbing the platforms, you often fall and lose your progress, this can become frustrating over a long period of time but in short bursts it's something I see myself sinking a lot of time into. I really liked the slingshot mechanic and can see that it would also work really well with the mobile touch screen interface.
The UI is very clean and intuitive and feels very professional.
The only things I'd like to see improved would be things like a frog sound effect would just add that little extra touch to really bring the character of Kaeru to life. The other suggestion I have is that the launcher is quite small and sensitive on PC which makes it feel a little more fiddly than it has to.
Must say I really love this one though!