Wow, great game! Very much a fan of the overall vibe of the game!
I had a lot of fun during each bossfight, the intro cutscene is also very polished and adds immersion, and the sets of attacks are varied and interesting to dodge (except some that I didn't get how not to get hit, like the beam attack of the 3rd boss).
The mechanic is really interesting, tho I think it's still not at its fullest potential yet. The "speed is your life" mechanic is very in theme with the game, but I feel like sometimes it can be a bit clunky, mostly because your only way of "healing" for now are spinners, that can be easily destroyed by bosses (they also take a bit too long to regenerate). Also, because shooting takes away speed, healing becomes a non-optional thing. I think the brushing mechanic of the spinner is a bit underutilized and too high risk, while I feel like that could be one of the most fun moves in the player's arsenal (the particles are amazing, I sometimes did it just for fun when I was sure I was gonna die).
I feel like this could also use some other ways to recharge speed: standing on a spinner waiting to be fully healed feels a bit like an interruption of the game flow, while I think more "dynamic" ways of recharging speed could make the game so much more fun and immersive! Or, make the spinner recharge you much much faster.
The audio and visuals are great, I like the low-poly-count aesthetic, reminds me of old games. the artstyle is very consistent so it feels good to play.
Overall, great game! I feel like the main mechanic has a lot of potential, it's a very cool idea!