I was very surprised to see an apk, so I had to leave a review
What I liked:
The simplicity of the game, it was immediately very clear what to do.
It was quite fun!
The upgrade system, which definitely motivates me to play more :P.
Things to change:
The volume starts at zero, so I assumed there weren't any sounds, but after going back to the main menu I could see the volume options. (Using PlayerPrefs.HasKey you can check if the value has been set before)
Move the player a bit up, because sometimes, especially in the beginning, you can collide with the clouds even if you can't see them.