Here is a quick experiment with Unreal Engine 4 (UE4) - there is no ambient occlusion painted on the textures as I do with Train Simulator - the building at Snells Nook is straight out of Sketchup 8 - the grass blows in the wind which actually looks quite nice - I have switched off the grass casting shadows to preserve frame rates - there are a couple of issues with the model such as some polygons are facing the wrong way and I've not yet figured how to export polygon smoothing groups - UE4 is using CM so the model arrives in UE4 100 times smaller than it should be unless I scale it x 100 on import. The transfer from Sketchup to UE4 was relatively pain free compared to getting it into Train Simulator.
Cheers
Paul