Cleared the newest patch, and the respawns seemed to work alright, but in some spots they could be abused to save time, so I'd suggest a time penalty for dying. Or a death counterat the very least. Here's some other suggestions that came to me while playing:
-Not sure how many songs there are in total, but could it be possible to make it a different one for every level?
-Having the BGM muted for the Tsunomaki Janken would make things less cacophonic, but I can also be a deliberate design choice and I'd respect that.
-It'd be interesting to see more variance in Watamelon's speed. As it is now there's the default speed and the charge speed. I think having Watamelon preserve momentum more would be interesting, and would work well with slope designs. I'm thinking of something like Hamsterball or similiar games.
-A personal high score list would be cool
-It would certainly make the game a bit harder but what if you couldn't steer Watamelon mid-air? It would make committing to jumps a more important skill. Also a way to adjust jump height by holding the jump button could work.
They're of course just suggestions since I'm no game designer :D
Your game makes me very happy and I'm excited to see what you'll come up with for the next update!