This is a comprehensive new tutorial from Jerome Renaux at Dynetis Games: "In this tutorial, we will see how to program the client and server of a very basic real-time multiplayer online game, and how to make them interact using Socket.io. In this small game, each player will move his character by clicking on the map, while the characters of the other players move in real-time on the screen. Although this basic game won’t be very fun, it will constitute a basis upon which you will be able to build your own exciting game."