I believe this prediction code wasn't included in the original Quake. It was added later in QuakeWorld which was some sort of multiplayer enhancement for Quake. Please correct me if I'm wrong.
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You may be right. I'm genuinely asking the guy if he knows one way or the other, as I do not know but certainly am curious. I mean, no lag compensation in the days of dialup? Seems like id/John Carmack would have know better even at that stage. But then again, it could just as easily be that they didn't realize the need for that tech in the beginning.
Even back then many people (including id software) had ISDN, T1s, or college connections that had the kind of latency most people have today.
This was also in the days when LAN parties and LAN events were much more popular.
I remember playing that first version over a modem, and indeed there was no client prediction at all. Not just shooting, but every single thing. You press forward, wait 300ms before anything happens, you switch weapons, wait 300ms. Even basic things like running and timing a jump over a small gap were extraordinarily difficult. But it was still kind of fun for the novelty of it, at least until somebody on a T1 or ISDN joined at which point you simply died before you even saw the enemy (ie. you saw them before you saw yourself die, but by then you had in fact already died on the server).