Why, what problems did you encounter?

Lots of crashes, broken quests and bullet spongy enemies. The Zone Reclamation project fixed all that.
It has been years since I played the game though (GOG version), maybe they modified something in the meantime.

Clear Sky I didn't even try without the patch.

I'll do the same with Pripyat.

The bullet sponginess of enemies depends on the difficulty level if I understand correctly. Basically the lower your difficulty level, the lower the chances of ALL bullets (including yours) hitting a target. So in some ways it's actually better to play on a higher difficulty level. I played on the second highest difficulty level ("Veteran") and didn't really have any problems. It's just weird design.
Can't remember much trouble with broken quests, certainly nothing that really hindered my progress. As for crashes, that almost never happened, probably not even ten times for all the three games combined.
I guess it was very different at the time of original release, but in 2018 (played them just a few months ago) I didn't encounter any serious problems.

Nono, I hit them in the head and they didn't die with bursts of fire. It is the bug where some bandits have like 100 times their normal health for a script bug.

Ah, ok, that does sound like a bug. Thankfully I never encountered that.

Stalker 2 came out ages ago :P https://i.imgur.com/sPwMqOF.png (running using J2ME Loader)

I couldn't agree more. It's also the best STALKER game of the three. As for Call of Pripyat, i recall i didn't encounter any problems playing it in the past (vanilla), but last night i reinstalled it along with Arsenal Overhaul (plus Absolute Nature & Weather) which makes shooting more enjoyable and deadly (headshot/neckshot equals kill, the same with 2-3 bullets in the torso). There may be better mods though; do you research if you plan to go the mods way. ;)

OMG YES! CHEEKI BREEKI!

I CANT WAIT TO SEE SOME IN GAME ENGINE SHOTS!

This is the best day I had in a long, long, long time. Thank you so much for posting this!

To be fair, TES did this, too. But, at least we can see from the way the games overall are played to see why the spinoffs were spinoffs.

This is good news. I loved Shadows of Chernobyl and Call of prypyat. Hated Clearskies. I build SmP for SHoC back in the day.. I wish I could have finsihed it.. But shit happends and Real life can screw ya.. :(

One of the best movies, ever.

S.T.A.L.K.E.R. 2 Dev Diary: Game Development During the War

S.T.A.L.K.E.R. 2: Heart of Chornobyl - Enter the Zone Trailer

I liked first Stalker but Ive a feeling this is another Metro.