Congratulations! By now, all your tests should be passing and your game should be complete. You have mastered developing a robust and well-tested API and deal with validation using reusable middleware. Along the way you've also learned to use Redis for a simple queue.
Now you can deploy your API and you'll have your Connect4-as-a-Service available for the world to build their own connect 4 game upon, using their own favorite platform. Whether it is an HTML5 interface, a mobile app, or a command-line interface, it will all be powered by your backend!
In the next chapter, we'll be taking game development to another level—it will be a realtime massively multiplayer online game!