CheckAppInstance

This plugin allows you to run only one instance of your game at the same time.
You can enable/disable check instance from the launch argument to the game binary file
-checkinst=<0/1|false/true>, this is useful for testing multiplayer game on a single pc.
Example: game -checkinst=0

C++/Blueprints functions:

• CheckAnotherAppInstance(bool IsEnabled = true)

ProjectSettings -> Maps&Modes -> Game Instance Class: BP_GameInstance

Install into Project

You can install manually by extracting archive CheckAppInstance-X.X.X-UE-X.X.zip from Releases to your project plugins folder
or build example project ExamplePrj-UE-X.X-CheckAppInstance-X.X.X.zip.

Install into Unreal Engine

You can install it from the marketplace CheckAppInstance

Manual:

1. Download and extracting archive CheckAppInstance-X.X.X-UE-X.X.zip from Releases to any disk path, for example: D:\Plugins
2. Than open any terminal (cmd, powershell) in D:\Plugins folder
3. Launch RunUAT in the terminal with arguments, for example:

Windows:

D:\EpicGames\UE_5.4\Engine\Build\BatchFiles\RunUAT.bat BuildPlugin -Plugin=D:\Plugins\CheckAppInstance\CheckAppInstance.uplugin -Package=D:\Plugins\UE_5.4\CheckAppInstance -Rocket

Mac:

sh "/Users/Shared/Epic Games/UE_5.4/Engine/Build/BatchFiles/RunUAT.sh" BuildPlugin -Plugin="$PWD/CheckAppInstance/CheckAppInstance.uplugin" -Package="$PWD/5.4/CheckAppInstance" -Rocket

4. If you see the message BUILD SUCCESSFUL in the terminal after the build is complete,
   copy the CheckAppInstance folder from D:\Plugins\UE_5.4 to D:\EpicGames\UE_5.4\Engine\Plugins\Marketplace

Important

The engine path and folder names may differ on your system.