[BSTRhino]

Actually, it doesn’t roll back the entire game state. Everything is stored in slot maps, and if there are 1000 slots and only 10 changed, it really does only rollback those 10 only and it does not touch anything else. Slot maps are great!

[mellinoe]

How do you accurately resimulate if you don't rollback everything to the previous state? E.g. a giant wall moved from point A to B but it was accurately predicted (no rollback). Don't you need to roll the wall back to accurately simulate everything around it?

EDIT: I misunderstood the previous comment, I think you are rolling back everything that changed, and not rolling back objects which were "static" in that timeframe.

[BSTRhino]

Yes, sounds like you get it, Giant Wall changed so it gets rolled back to point A, then it resimulates, which might mean Giant Wall might push some other things this time around that it didn't before during the predicted simulation. It kind of uses a transaction log copy-on-write kind of mechanism, so there will be a log entry for previous value of the Giant Wall slot and it will restore that into its old slot. It's a bit more advanced than that but that's the gist.