I was pretty heavy into CS 1.5 and 1.6 from about 2000-2004, hell I'm a Steam day 1 adopter because that was the only way to get 1.6 (although for whatever reason Steam says I didn't join until December 2003). I stopped playing around the time CS: Source came out because it just seemed to be random headshots everywhere due to the new engine. Also for the amount of time I was putting into it I wasn't getting any better and that was a little discouraging. I bought CS: GO back in 2013 for a sense of nostalgia and I still suck at it, in fact I think this
webcomic sums it up pretty well.
Day of Defeat was significantly better.