We created an Express app, a Socket.IO server, and a game client that can talk to our server using the socket.io-client library, and receive the push updates from our server. We've also gone through the user creation and word chaining logic so that we can validate new users and words to be chained. In this process, we dived into the world of Promises; hopefully, illustrating their versatility and how they can simplify your code.

In the next chapter, we will introduce how to build a user matching system, and make it a service. You will also learn how to set up periodical tasks with node-cron.