Just press the green flag and it should create it's own roller coaster with a cart moving along it.
I made this myself. I created this by first taking a sprite and make it just run a randomly generated path. Each step it takes it records if it went straight, up, or down. Then we make the cart and run it along straight, up, and down, trying to keep to the memory variable recording what it needs to do. Also, due to the fact that I don't want it going too high or too low and the cart is slightly higher than the track, if it goes too high or too low then it may break and the cart will just be doing the track just... Not on the track.
