The Metro’s series’ stealth elements is imo one of the GOATs despite not being anything special mechanically.
I say this because of how natural the enemies behave and what actions they are taking up. If you are careful and don’t cause any alerts to go up then you find that most NPCs are basically chilling out, they’re sat around drinking, gossiping, getting on with odd jobs or hiding away in some corner skiving off. Even patrolling guards will actually stop off at points to talk with others stuck on guard duty or get distracted. You can also create distractions without immediately convincing them it’s an intruder in the base.
If you do wind up causing them to raise the alarm without being spotted then everyone freaks out but it still feels natural, they act spooked and worried, moving frantically or hiding if they aren’t a combatant.
It’s such a big gripe since playing the series that I have with other games that pride themselves on being stealth games, like Ghost Recon, Far Cry, TLOU 1 and 2 etc theres no way even professional soldiers can be at constant back and forth readiness 24/7 they never tire or get distracted or complacent and it’s such a shame only a few other games like Hitman or MGS don’t factor in this natural and immersive element to their stealth segments/gameplay.