Algodoo

I've never seen one of these yet, ive seen mechanical ones, but they sometimes fail:(. drive the cars with arrow keys, reset the loop with L. If it doesn't work then make sure the collision group of the darker bits of track are {scene.my.loop1}. the wheels of the rollercoaster collide with the black box and it switches the collision groups of the track. please dont press undo it breaks all of the scripting.(well on algodoo) this scene also works on the phun edition of algodoo