First of all, in general, the game is really well done—both the music and gameplay feel great. However, on PC (at least from my perspective), using the mouse can be uncomfortable. The digital joystick is very small, which becomes bothersome when trying to move it quickly. For example, you might end up making a 180° turn when you only meant to make a 90° turn. Adding an option to increase the size of the digital joystick could be a good idea.
Secondly, I feel this might be intentional since it's just a demo, but it seems odd—especially since resources remain even after upgrading all the skill trees after the first match. Also, I find the skill trees to be a bit unintuitive. For example, having to move back to an upgrade button to improve a trait, rather than having the option to double-click directly, feels cumbersome. I also think adding a button to undo the last change or reset the upgrades wouldn't hurt. Another thing I believe could improve the experience is if you could view all three upgrade tabs at the same time on the same screen, instead of having to search for them at the bottom.
I hope none of this comes across negatively; I’m not an expert in video games (I just play them), but I really like your project and hope you can keep improving it. I also hope my feedback helps you do so. Of course, if anyone else wants to share their thoughts, they are totally free to do so. I’m just speaking for myself. Until next time! :3