If Run8 crashes before even reaching the Main Menu or during the Loading Screen, you almost certainly need to install the Jun2010 DirectX Redistributable and\or VC_redist.x64.exe found in the following location (assuming a default installation location):

C:\Run8Studios\Run8 Train Simulator V3\Redistributables

There, you will find an Instructional PDF that will assist you with installing these redist packs.