I'm no longer in the game, but circa counter-strike 1.1 or 1.3, the typical way was using windows hooking API to load your hack into the running process. You co

I'm no longer in the game, but circa counter-strike 1.1 or 1.3, the typical way was using windows hooking API to load your hack into the running process. You could then simply use the freely available half life modding sdk to use the same structs and things like that. Network related stuff also happened, but I never paid attention to it.