Lovely graphics. I had to use the arrow keys because WASD didn't work so got a bit frustrated trying to get teh bunny to respond but only turning the camera with Q and E. I built the loop easily and that mechaic worked really well! It was clear and similar to other track building games. Maybe more of a challenge like a timer before the train start to follow the track forcing you to complete a loop would have been a bit more exciting.
Overall, well done! Beautiful art style! So cute.