They physics are actually deterministic with avian. Its a fantastic physics library, especially with observers, makes implementing collision detection a breeze!
So glad to hear you had fun, I had it at some point that you would see your full path (or a much larger path) but then thought it would become too trivial to build the combo machine...
But probably should have implemented it as an upgrade for the shop. If I just had a little more time... :)
Thank you for trying it out!