Comment by yakcyll

There really doesn't seem to be anything new or unique to their solution. I'm personally not surprised, because it is what has worked for thirty years.

I presume you know this, but maybe for others: judging by what was written in that paragraph, I'd indeed assume he means the same paradigm that has been driving replicated real-time simulations since at least QuakeWorld - some world-state updates (in this case _"object transforms, velocities, and player positions"_, among others) don't have to be reliable, because in case you miss one and need a retransmit, by the time you receive it, it's already invalid - the next tick of the simulation has already been processed and you will get updated info anyway (IIRC this is essentially John Carmack's insight from his .plan files).

The command messages (player operations and events) _need_ to be reliable, because they essentially serve as the source of truth when it comes to the state of the world. Each game client depends on them to maintain a state that is the same for everyone (assuming determinism the Teardown team has been working on ensuring).