I was trying to think of which games created certain mechanics that became popular and copied by future games in the industry.
The most famous one that comes to my mind is Assassin’s Creed, with the tower climbing for map information.
In a way, I’d say World of Warcraft (2004 onwards) popularized that.
Here’s your starting place. Here’s a bunch of easy quests and monsters.
You quit the starting area. Everything feels huge and really, really fucking far away. One step in the wrong direction and you’re assaulted by an enemy with a 💀 for a level. Not only that, most people would only see the loading screen once before doing an hours-long playthrough and that also increased the sense of “fucking huge world”