3. Writing a server side handler.

To implement your feature in your multiplayer game, you need to use socketIOs Events system. For that, go in the main.ts file. Note that you will need the Typescript compiler. I recommend to use WebStorm IDE from JetBrains as it automatically handles that for you (it is paid tho(it is free for students tho)). Here, go to the part with socket.on("auth"). Inside the function passed to it, add a new socket.on("your keyword", function(data){your function that implements your feature}) definition (Of course modify the obvious placeholders with your own code). Then compile the ts files and try to execute the server.