Cute game - it's a clever idea that you slowly earn points on the design phase that lets you buy more pieces. It's seem like there's some idea of creating loops on the design phase to increase the numbers before the time is up. I'm not sure what I think about this because building the engine and running it felt more satisfying
It could be cool if there was more pieces variety like junctions and conditional parts (maybe there are, I'm currently at the 2nd level).