That was the solution:
$ cd "~/.steam/steam/steamapps/common/War For The Overworld/WFTOGame_Data/CoherentUI_Host/linux"
$ file CoherentUI_Host
CoherentUI_Host: Bourne-Again shell script, ASCII text executable, with CRLF line terminators
$ dos2unix CoherentUI_Host
dos2unix: converting file...
Yes, I have read it and tested parts of it, some time ago. Unfortunately I cant remember which, but I do remember that none of them helped ultimately, since I dindt get the game to run.
So I just tested the switch to nvidia-prime again, and got a crash. Log is attached.
That is what i meant with editing the xorg.conf. I would had to choose between long running time and low energy consumption and playing all the other games (intel with bumblebee switching to nvidia) or playing WTFO (nvidia proprietary)
I got another 3d game (http://www.verdungame.com/) which also uses Unity. It runs perfectly with bumblebee since I got it a year ago.
I cannot be the only one who doesnt want to change xorg.conf every time I start up WFTO!
Running bumblebee-nvidia 3.2.1-90~trustyppa1 i cant get 3d to work properly. Instead I get a black background (see attached file War For The Overworld_012.png)
When I scale the window i get a glimpse of the correctly rendered background, until Coherent_UI draws over it.