Glad you liked our game! Thank you for your thoughtful feedback.
The game actually has three paths. The one would lead to full plant growth, the second to full tube growth but a dead plant and then, there is a balance path, if you choose to take care of the Tube and plant equally. This leads to an ending which is difficult to achieve but the happiest.
I agree that the mini-game/keyboard can get monotonous. In the limited time we had, we added a 'skip' button for this reason.
I also agree with your suggestion regarding having more songs in there.
We initially had keyboard controls but they were difficult to use and would not be playable on a touch-device. Though this suggestion is also something we will look into post-jam.