Everything that you've done up to this point has been about getting players in the same match, but we haven't covered anything about keeping in-game events synced between the server and client. Fortunately, Unity's networking API makes this very easy; we can use most of the code we've already written with some slight modifications to make it network-aware.
The first thing we'll tackle is player movement, so you can see other people walking around the map. We'll build upon our existing player prefab and the NetworkIdentity component, as well as a new kind of component: NetworkTransform.
Select the ArenaPlayer prefab in your Project window and add a NetworkTransform component in the Inspector. This alone is enough to sync the position across the network but, if you tested now, you'd run into an interesting problem: input from any player would be reflected on every other player instance in the game. This is because there's one instance...