I don't think it did officially, there were definitely server plugins that did it back in the day but AFAICT it wasn't official until this 2015 update:

https://old.reddit.com/r/GlobalOffensive/comments/37ebes/maj...

> Added trace-based visibility checks to prevent networking invisible enemy players.

If you're remembering playing with the r_drawothermodels console command to get a faux-wallhack effect, that was still subject to the engines clientside occlusion culling so it didn't show everything the client (and real cheats) were actually aware of.

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.

Yeah that's the same deal as r_drawothermodels, crudely forcing the GPU to render objects that are behind other objects would give you a partial wallhack, but clientside occlusion culling was still in effect so once it determined that an object was definitely no longer visible it would skip drawing it altogether, and you would stop seeing it through walls. "True" wallhacks were able to override the clients occlusion culling and reveal everything, so to defend against that the occlusion culling needs to happen on the server, which came much later.

Oh interesting. Thanks! We must have assumed it was client-side and gave up.

*server-side