There should be designated tracks that can carry the cart uphill, and the physics should be more realistic if the cart hits uphill at too slow speed and can't climb it.
Well what i figured was that when you go to slow you get pulled. In other words even though you don't see it but when ever you need pulleys they are placed on the tracks.
As for making it so you pick when they go in or not, i feel would rise the learning curve to high. But I have heard this suggestion just one too many times. So ill figure something out, maybe add sound when your being pulled so people can tell your on a pulley and/or a model.
Lastly, do you plan on creating terrain that is more of a theme park atmosphere?
Well Yes and no. Yes I hope to get someone who has terrain talent as most everyone says my terrain skills suck, to do some work on the map at some point. But its really not my area of skills.
Approved
