All multiplayer games sync a queue of messages to derive game state, that’s inherent in networking.
Deterministic lockstep means that the speed of the simulation is dependent on the slowest member as everyone waits to get all the inputs before advancing a frame. You’ll get literally pauses and jank if someone is on a poor connection. That’s not the case here.
The difference with this model of networking is what is synced in the lockstep case the simulation being deterministic means you only need to send inputs to keep the game in sync so you vastly reduce network traffic. In this case it’s not necessarily deterministic and the server sends back the new state to the clients after determining what it is as it’s the authority on what that state is. Clients can predict ahead by making the change locally but must correct mispredictions. In the deterministic case there can be no mispredictions and it’s a pain in the butt to ensure that your game is actually deterministic and resolving sync issues is a real pain.
Factorio sounds like it uses a deterministic model that doesn’t wait to run in lockstep and instead reconciles errors that causes. The typical way of doing that is to rollback to a prior state where the simulation diverged due to missing inputs and redo the following ticks. That’s probably prohibitively expensive given the scale of Factorio versus something simpler like a fighting game so I assume there is a hybrid model and some extra info is sent by an authoritative source that can be checked locally.
Deterministic lockstep means that the speed of the simulation is dependent on the slowest member as everyone waits to get all the inputs before advancing a frame. You’ll get literally pauses and jank if someone is on a poor connection. That’s not the case here.
The difference with this model of networking is what is synced in the lockstep case the simulation being deterministic means you only need to send inputs to keep the game in sync so you vastly reduce network traffic. In this case it’s not necessarily deterministic and the server sends back the new state to the clients after determining what it is as it’s the authority on what that state is. Clients can predict ahead by making the change locally but must correct mispredictions. In the deterministic case there can be no mispredictions and it’s a pain in the butt to ensure that your game is actually deterministic and resolving sync issues is a real pain.
Factorio sounds like it uses a deterministic model that doesn’t wait to run in lockstep and instead reconciles errors that causes. The typical way of doing that is to rollback to a prior state where the simulation diverged due to missing inputs and redo the following ticks. That’s probably prohibitively expensive given the scale of Factorio versus something simpler like a fighting game so I assume there is a hybrid model and some extra info is sent by an authoritative source that can be checked locally.