We're recording the integer clocks though, and those don't change between runs. While game code converts things like (QPC ticks over tick-rate) to floating point, we don't sum those numbers directly. Instead, we internally store times as the raw integers then convert them to floats on-demand (typically when an Update function is asking for "elapsedTime" or a timer is asking for a "timeSpan" (like time since the start of the game.))

LoL and TFT don't use a synchronized-simulation (lockstep, sometimes called peer-to-peer) networking model. LoL is Client-Server, meaning the replication is explicit and not based purely on playing back client inputs. This gives us more control over things like network visibility, LODs, and latency compensation at a feature-by-feature level at the cost of increased complexity. Most of the games I've built over the years use this model and the LoL team is super comfortable with it.

The GameClients are not deterministic in the way that the GameServer is, though they're naturally closer to that ideal since the GameServer itself is typically predictable.

Don't get me wrong, there's a time and place for lockstep replication, and LoL probably could have gone that way. I wasn't there when that direction was picked, but I would have likely made the same choice as my predecessors, knowing what I do about our approach to competitive integrity.