Solution 1:
Open Steam, Rightclick on the Tourist Bus Simulator -> "Properties" -> "Local Files" -> "Verify Integrity Of Game Files"
Solution 2:
Open Steam, Rightclick on the Tourist Bus Simulator -> "Manage" -> "Browse local files"
Now the Tourist Bus Simulator Folder should have popped up, navigate to: Fernbus Simulator\Engine\Extras\Redist\en-us
There you should find a installer called "UE4PrereqSetup_x64", run it as Administrator and try to start the Tourist Bus again.
Solution 3:
1. Uninstall the game via Steam
2. When uninstall is done please open the folder:
C:\Users\YOUR_WINDOWS_USERNAME\AppData\Local\TouristBusSimulator\Saved
Alternativly press Windowskey+R copy/paste: %localappdata% with the %-letters and follow the path above to: TouristBusSimulator\Saved
3. Delete all folders except "SaveGames"
4. Go back to: C:\Users\YOUR_WINDOWS_USERNAME\AppData\Local\TouristBusSimulator\
Delete the folder: "Settings"
5. Open your Steam Installationfolder:
XYZ:\Steam\steamapps\common
Delete the whole "Tourist Bus Simulator" folder
6. Restart your PC and Reinstall the game.