I'm referring to CS 1.2 or so, back in ~2002.

The thing I remember was that my friend's graphics card had a global transparency setting built in (AKA a wall-hack mode lol). You could see other players come into view as soon as the came into an area that was rendered. Then a CS patch came out and the players weren't visible until very shortly before they would become visible had we not had the uhh... transparency mode on haha.