HI, I own a copy on a laptop. I have given this to my son as I have upgraded so he can play J.E. as he only has the ps4 version. I purchased another copy using his new steam account on the older laptop and he is well chuffed. Now I want to play co op with him but when I launch from my new laptop after re-installing from my library it fails. It flashes the first time setup window for a millisecond then reverts back to play button. when browsing local files there appears to be no exe. file. Can't get a screenshot but its steam/steamapps/common/terraria. The file exists on my sons copy. we beat the game together way back on the 360 when he was 5, he's now a "pro" lol any help would be as you can imagine greatly appreciated. By the way tried steam forums and support sent me here.