[insraq]

Just want to chime in that although this comment is a bit harsh, it does hold a lot of truth. As a game netcode engineer, most of my time is spent on latency hiding techniques and its consequences (for example, we use rollback netcode and lots of efforts are spent on minimizing visual/sound glitches when mispredict, rollback and reconcile). There are lots of middleware that help with this (eg. Photon, SnapNet, etc) but in general there's no silver bullet - it's highly gameplay specific. Even for the same game, the solution can vary depending on different trade-offs (i.e. budget, correctness/anticheat).

As to how to store the game state in memory, it's usually not something that needs much thinking: it's simply done the same way (or similar) as the game's client code. After all, netcode is mostly about efficient state replication and this saves CPU time when replicating it across clients - and gives more CPU time for minimizing bandwidth (like delta encoding, quantization, etc). If you want, you can utilize some techniques like ECS to optimize for CPU cache locality, but it affect gameplay code a lot and would need to get the whole team onboard.

Also, I just noticed the username "gafferongames" - Glenn's blog[1] has been a must-read for netcode engineers. It helped me a lot when I started working on netcode in the 2010s

[1] https://gafferongames.com/