First of all, great job to the developers. Shaping this type of game around such a cute skill tree is a fantastic idea. However, the lack of a lose condition or a specific goal makes simply unlocking the skill tree feel a bit insufficient. In my opinion, the absence of any objectives, competition, or time limits makes the gameplay dull after a while.
Additionally, I noticed a balance issue in the skill tree: when you acquire the "Laser Beam" skill, the lightning continues to strike and earn points even if you go AFK and leave the game in the background. Instead, to make it more engaging, the laser beam could be adjusted to activate once every two cannon shots, for example.
I also encountered an audio bug: when I turn down the music and SFX volume, the sound effect for the "Pinball Time" skill remains at the same level, unlike the other skills. Since I haven't tested every single skill, I'm not sure if others have this similar issue.
Overall, the core concept is really successful, and the skill tree design is quite sweet. I have absolutely nothing bad to say about the art style, music, and effects—they are flawless. I hope you continue to develop the game!