Add the following 3 configurations to "Run/Debug configurations". All of this configuration should be build under Java 11.
Config Name: Server
Main Class: de.thundergames.MoleGames
Program arguments: s
Config Name: AI
Main Class: de.thundergames.MoleGames
Program arguments: "a" <ip> <port> <gameID>
Info: Under "Modify options" select "Allow multiple instances.
Config Name: Player
Main Class: de.thundergames.MoleGames
Program arguments: p
Select the Server configuration and start it.
Select the AI configuration and start it. You can do it multiple times until the game is full.
Select the Player configuration and start it. Logindata: Name: [insert your name] IP: 127.0.0.1 Port: 5000