Dead Island Riptide will not work

This weekend there was a 50% off Dead Island Riptide sale on steam. Me and my brother both bought a copy, and i started the game up perfectly and started the prolouge. However, my brother couldn't. ME and him have near identical machines... I've got a i7-3770k, he's got an i5-3570k. He's got an AMD 7770, I've got a GT 640 (for the time being).The only thing is... my brother can't start a new game so that we can play the coop. He can't even play single-player. This is extremely frustrating as we've spend 40$ on this game and can't even play it.

 

Any and all help is appreciated.

What error message does he get?

 

Till more information is available do these:

  • Update CPU drivers
  • Update/Install Motherboard drivers
  • Make sure the game path is not too long (Like C:/extremelyLongFoldernamehere/Evenlongerfoldernamehere/Steam/Steamapps/Common)
  • Direct X Install/update

 

Also what version of Windows is he using? Could try compatability modes