modify the existing node.js application

Hi, I have a node.js express application. I need to modify one function. The source code is in here [login to view URL] We deployed the code into [login to view URL] I want to modify the create game logic. right now if you click play you will start the game and create the URL for the other player. you need to copy the url and send it to the other player. once they accept the request then you can start to play each other. I want to modify to you click play then send the play request to the other online player. once they accept the request then you can start to play each other.