How Do Video Games Stay in Sync? An Intro to the Fascinating Networking O (Cont)

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  Multiplayer game framework (by hathora)

  

I've been working on my own realtime networking engine[0] and I think there are a few important points related to network syncing that are not mentioned in this article:

1) Bandwidth. The users internet can only handle so much network throughput, so for fast paced games (where you're sending data to each client at a rate of 20+ frames per second) it becomes important to optimize your per-frame packet size. This means using techniques like binary encoding and delta compression (only send diffs).

2) Server infrastructure. For client-server games, latency is going to be a function of server placement. If you only have a single server that is deployed in us-east and a bunch of users want to play with each other in Australia, their experience is going to suffer massively. Ideally you want a global network of servers and try to route users to their closest server.

3) TCP vs UDP. Packet loss is a very real problem, and you don't want clients to be stuck waiting for old packets to be resent to them when they already have the latest data. UDP makes a major difference in gameplay when dealing with lossy networks.

[0] https://github.com/hathora/hathora

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• GameNetworkingResources

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  A Curated List of Multiplayer Game Network Programming Resources

Honestly this is all largely a completely solved problem space. The article is just way out in left field seemingly fully oblivious to how game netcode currently works, which certainly isn't with AI prediction.

Look at actual game engine docs like this one from Valve https://developer.valvesoftware.com/wiki/Latency_Compensatin... or this one from Halo https://www.halowaypoint.com/news/closer-look-halo-infinite-...

But tldr is the only thing a client ever predicts is their own inputs, which of course can't really ever end up wrong later on. There's no other prediction happening (eg, the position of other players is not predicted)

And then for anti-cheat/optimization purposes the server also only sends positions for enemies that could be visible soon, which is done by taping into the same map chunking logic that would be used for asset streaming.

There's a ton of other great resources on this topic here https://github.com/ThusWroteNomad/GameNetworkingResources

But you'll find they all largely do the same basic thing. There's nuance in some of the rules and what state is replicated and what isn't (such as server side or client side ragdolls), but the general architecture tends to be the same. And without a fundamental shift in connectivity, seems pretty unlikely to change.

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