I remember I got it for GMod, and played it out of boredom one day and I ended up loving it!
In 2007, DirectTV killed the North American professional CS scene by pushing CS:Source into their televised CGS league. The top pro players all left the 1.6 scene for 30-40k/yr contracts to play in CGS (a no brainer)... most of them openly hated the game while playing in this league too. The 1.6 scene in the US was still large and active, but never the same. Teams in Europe, Asia, Brazil & elsewhere continued to play 1.6. After CGS folded in 2008, global competition sort died off and many of he top NA players retired. There weren't many NA 1.6 players good enough to keep up with European pro teams after about 2010.
Imo, CS was an incredible scene from like 2000-2008. CSGO has enjoyed a great run from like 2013-2018?. It's definitely lost steam from the battle royal shooters (PUBG & Fortnite), and now Valorant infringing on it's player base. Valve hasn't really been very active in its own competitive scene, which may also be hurting.
Some of my CSS memories - We used to shoot barrels on top of the bomb that would prevent defuses until you shot them off. If you didn't have a grenade or extra ammo (pistol rounds?) this was hilariously difficult. Leagues had to ban this tactic, but there was no setting to just get rid of the movable barrels so it still happened occasionally.
- There was a bug where a players view would sit above their player model - so they could duck behind a box and see over it without being seen. I never learned how to abuse it, but it was obviously very effective.
- Head hitboxes were bigger in CSS than 1.6. The game was just easy.
- The deagle was way too good in CSS.
- Hacking in CSS was really bad. It took a while for 3rd party anti-cheat clients to catch up. League play was plagued by hackers.
- CSS had ragdoll physics instead of death animations. Occasionally players would die while sitting or leaning up against a wall. If you took a quick peek this might make you think it's a player crouching and still alive. The ragdoll deaths made it harder to detect if a player was dead or not
- if they were running at you and died they might still be falling forward in what looks like a running/ducking animation for 100ms or so.
- The maps were needlessly complex. The addition of flower pots, cans, trash, arches, window sills, steps etc etc made grenade physics less predictable. There were times where trash would block a doorway and make entry into a site impossible without sounds from it as you walk over. CSGO has this same problem, even with the chickens. (https://www.reddit.com/r/GlobalOffensive/comments/7ygcve/chi...)
- I remember play shadows being something that was a huge competitive advantage for players with a better PC. If you set your shadow quality too low, you wouldn't see them - and there were certain areas where you could see a players shadow if you had the setting on high.
- Bullet impacts into walls were harder to see because of how "dusty" CSS was. When you sprayed into a wall, the clouds of dust that would come off made it hard to see where the shots were landing. CSGO greatly improved this. (https://youtu.be/Y4TVegjgvXc?t=180)
I could go on - obviously I kinda hated the game, but I also had a trash PC at the time and was fraggin out with 45fps-110fps and a single core processor for a while.
I played CS 1.6 on a Pentium 1 133mhz processor and no discrete gpu and it worked fine, though I did eventually get an athlon xp 1700+ and geforce 3 ti 500.
The game ran on practically everything.
In the end Valve supported CounterStrike whilst ID software did not support mods at all for their platform which in turn sealed the fate for Actionquake2. There was attempts to port it to Quake3, but the gameplay never compared.
Some of the same people were behind Actionquake2 and Counterstrike and there's an argument to be made that AQ2 was the proto CS game.
One other change I remember is that the AK became a proper sniper weapon. It was a little more uncontrolled pre source.
You have to remember, these kinds of games ingrain heavy habits. You get a feel for various nuances in the game (eg shooting people through a wall, recoil of a certain people). They may feel surface level but it can be jarring when it all gets changed.