Do you want to run multiple game windows from the editor?
No it’s shipping build . I need only one window to start. And when you try to run more windows, they would not start
Do you want to limit game instances to one and don’t allow to launch more?
It may be ticky but I think you will need to check if process with similar name as your game exists and if so than don’t run.
Seams there no way to do this without C++, most less invasive way is to on C++ module startup (or make new module with earliest LoadingPhase) or at least overall start up of the game, check if process is running this function:
FPlatformProcess::IsFirstInstance()
and close game if it return false