Really good racing game, feels very polished, had lots of fun with it! Setting a racing game inside blood vessels is surely interesting, indeed a strange place! Liked the gameplay a lot, without reading anything I was a bit confused on the mechanics but quickly figured them all out and got comfortable with the controls (I also like that movement keys are clearly explained at the start, it is not granted one will know what to press). I just found a bit difficoult to clear the plaque as you often already go so fast you can't even notice it, and you end up missing it ot clearing it without realizing, but that's not a big problem.
I liked the velocity depending on the heartbeat, and just as a little nitpick I'll say I would've liked if the indicator was a bit bigger rather than small on the side of the screen, but I quickly got around it following the rythm.
I liked a lot the mechanic of your previous matches being recorded and replayed on the next play, thus creating a sense of competition with yourself rather than a simple want to get a higher score. Genuinely one of the features that would keep me playing the longest.
And I liked a lot the general skill ceiling of the gameplay!
Visuals and sound are very good and clear, very polished!
I just wished there was a bit of extra variation on each track, a good example being the one with the big line of plaque, that needs you to catch it and keep that side to gain max velocity, but that I know it's too much as time was what it was.
Great job! Very fun game!