Gothic 1 got overshadowed - especially in the west - by The Elder Scrolls, but to this day it remains the most immersive RPG I’ve ever played.

• Before Oblivion’s “radiant AI” it had full schedules for every NPC. They sleep, eat, go to work, sit around the campfire talking, …
• It has a full open world (admittedly smaller than Vvardenfell) with no loading screens except when going underground. That includes houses: everything is one world.
• NPC reactions that make sense: start to sneak and they’ll ask what you’re doing. Draw your weapon and they’ll draw theirs and tell you to put it away. Enter their home and they’ll chase you out.
• Animals in the wild are not just there for you to get XP. They eat, scavenge, hunt, and sleep.
• Speaking of animals, they’re also not constantly in a “must murder the player” mode. Non-aggressive species will warn you not to get close, and only attack if you don’t back up. Others may stalk you, seeing you as prey. They just make sense.
• Stealing also makes sense: if nobody saw you do it, you don’t get in trouble. No loot ever gets a red “don’t buy me I was stolen” mark on it.
• And so much more.

If I sound like I’m picking on The Elder Scrolls, I kind of am. I actually do like TES, but I wish more games took inspiration from Gothic.

There’s also a remake, which is too recent for patient gamers (and for me), but it’s getting good reviews. And there are sequels and spinoffs, some more liked than others.