I tried all know methods to run "unathorized" apps and only one worked for me:
1. Start Terminal
2. Enter sudo spctl --master-disable
3. Conform it by entering my password
4. Right click on Saboteur 3D, then click Show contents. Then open Contents / MacOS and double click on Saboteur 3D.
5. Game runs or ask for Open and then runs.
But it's working for me on my Mac and not working on my GF's Mac.
But all previous games including Laser Squad are working just fine. Kinda strange.