The concept behind this game really has legs, but there's too many roadblocks in the way. Races are very slow; waiting 2 minutes for the slowest CPU is frankly too long and I alt-tabbed out most of the time. It's most glaring at the beginning when you can only afford two wide corners and the only interactivity is pressing accelerate at the start. Additionally, there's no incentive to build different tracks -- a rectangle with tight corners can be constructed by the third race and after that, you can win every time. I really like the sandbox idea, but when the optimal route is also the least fun one, it's hard to go past that. I'm hesitant to suggest adding mechanics because of course every game jam game would be better with more things, but varying map obstacles that force experimentation would go a long way to fleshing this game out. The flow between constructing and playing you've come up with here is inventive and fun, and with a bit better implementation, it would be really fun.