Whilst at the time it was revolutionary it was always extremely buggy and broken.
There were physics in play making you a poor shot no matter how accurate you were, enemies were bullet sponges and the "hack" that fixed it and made you a better shot also made them better to the point where they were all marksmen.
They then went bankrupt and IIRC were bought out by THQ and Clear Sky was just another big fat ole mess.
Call Of Pripyat is the one to play if you want to have a go.
There are some mods, like the remaster and others that made it really good. Like Stalker Complete. I can't remember the name of the mod I used, but it left the game almost entirely intact but tweaks some poor mechanics and eradicated all the bugs. Love this game.
Same. When the first game came out, I didn't have a rig that could play it. Once I did, I just had other games on backlog that I wanted to try first, then new games kept coming out. I have them all on Steam. I think paid less than $10 for all three a few years ago.