Congrats on the work you've done, however, there's a lot that needs to be improved for the game. On the plus side, your visuals are real nice. The graphics are good for the tracks and the vehicles, the visual effects are nice, and I don't seem to notice the lag issues others complain about so maybe it has to do with processing power. The controls are real smooth as well. I haven't seen too many if any racing games that use keyboard controls without an acceleration button but yours pulls it off well.
However, as a game it seems lacking in gameplay. I'll ignore the music issues since it's my fault I can't run the unity version, but hopefully I can find some of the soundtrack for this game so I can take a listen (and possibly play some of it in my video of it). Many of the tracks are shorter than the loading screens it takes to load them. There isn't anything exciting going on. I will admit that I'm more used to racers like Mario Kart so that does play into issue. However, even when I had other people to race against, I didn't really feel like I was racing them, just that I was driving on the track. A lot of the tracks I tried didn't really feel special either but there were so many tracks that if there were good ones, they were lost in the sea of average or subpar ones.
There's a lot of areas to fall off the track in later courses and while the reset button solves some of those issues, many racing games will reset you to around where you fell off in this situation automatically. On harder courses it can be annoying to redo everything over again just because you fell off. Speaking of falling off, one of the tracks I tried had a very hard jump to make, even when I didn't hit any walls and thought I got as much momentum as I could, sometimes I couldn't make it. Shame considering that course seemed like the best one in terms of length, look and things to do. I would tell you which one it was, but all the tracks had uninspiring names and I couldn't remember those names for the life of me. Plus some of them had the same exact name.
Again this is a nice looking game, but it lacks the feel of a game due to elements missing that tend to be important for a racer, like a sense of competition even against AI or a clock, the tracks, and the rewards not making the race feel rewarding enough. I have to be honest, because you did ask me to review this game and it would take away the whole point of reviewing it if I didn't point out these things.