He was involved with the development and helpled make sure it was going in the right direction, but he was not involved on a full-time basis. It's just basically a direct port of Rollercoaster Tycoon with 3D and more effects added so his direction isn't needed too much.
I will only buy this game if the excitement and intensity levels are back, thats what really seperated it from the unrealisitc montrosity of theme park world.