By my numbers (though as you can clearly see from the link I posted, >200ms latencies are not uncommon), and Carmack's assumptions in 1996 about what latencies would be acceptable.
> So he designed for 200ms and then the real world was 300+ so it didn't work. Your 100ms would then work fine in that context.
He designed for <200ms which by the frame of reference he cites (T1 connection) probably was a lot lower than 200ms on average.
> Maybe games have gotten more complex or our expectations higher so prediction is still worth it even on <50ms connections.
Quake was not a very complex world, but more important (to latency) is that it's a fast paced game by today's standards (IME). It seems more likely to me that perception on what an acceptable hand to eye latency is has changed, just like the perception on acceptable frame rates. To me, joining an online shooter with >100ms latency (even with prevalent client side prediction) feels debilitating, especially if other players have lower latencies.
> But OPs point that the assumptions underlying Carmack's redesign have once again shifted seems correct, at least for that specific design.
Yes, I agree that PPP and SLIP are not common any more. High latency unfortunately is, and client side prediction is still an effective mitigation strategy that makes a huge difference to online play. The specific design used in Quake has of course been superseded.
Those numbers match my experience a long time ago with Quake3 based games where you'd pick servers that are local to you and get 10-40ms latencies.
> He designed for <200ms which by the frame of reference he cites (T1 connection) probably was a lot lower than 200ms on average.
I didn't forget the < sign. Designing for <200ms means you can handle the 200ms worst case. But maybe he meant 200ms worst case but much lower average like you are suggesting.
> It seems more likely to me that perception on what an acceptable hand to eye latency is has changed, just like the perception on acceptable frame rates.
Right, makes sense that the expectation today is much higher.
>High latency unfortunately is, and client side prediction is still an effective mitigation strategy that makes a huge difference to online play.
Just for curiosity, how low does it need to go for prediction to no longer be useful? I guess if you want to be able to have players from all over the world play each other then you have to deal with 300+ ms of latency. But if you are willing to do servers on each geography it seems 10-30 ms would be feasible. Would that be enough?
10-30ms is a bit optimistic, depending on how large you define a geography. Many ADSL/VDSL connections, best case, start with 5ms of latency, and often higher (say 20ms) due to interleaving. Cable tends to be around 10ms IIRC but can suffer from significant jitter which makes things worse. So for a lot of players the servers would need to be in the same city to achieve that target.
Just checked my fiber connection and it has 2ms of latency. google.com is 18ms away. I'm in Portugal and seem to be routed to a Google server 400+ km away in Spain. So my memory of playing on 10-20ms to local servers in Portugal is probably accurate. Covering the US or the EU with enough servers so everyone is never more than 30ms away seems feasible. Within easy reach of a startup with just ~50 VMs across different cloud provider locations and for popular games easy for users to setup regional servers themselves.