[bri3d]

This kind of determinism testing is a fairly common approach in games that implement shared-state multiplayer, and I think that's why it was implemented for Factorio as well. Otherwise you get drift between clients that breaks the game.

[TrainedMonkey]

One alternative is to run everything on the server, but that introduces another set of problems.

[m4rtink]

IIRC that's what Satisfactory does and it causes all sorts of synchronization issues and glitches - non-hosting players not seeing buildings or stuff on belts or even glitching into/colliding with things that were not there a split second ago, as they loaded from the server too slowly.

That won't really happen in Factorio due to the shared state & makes possible insanely complex layouts that all players can see an interact with exactly the same. The downside usually is that eventually - just after you got that 20 GW nuclear power plant with trucked water & and steam going - the slowest player starts to have issues as his hardware no longer can keep with the complexity of the simulation.

Then you either start shedding players or call it a day and start again with a different objective or mod.