I'll state an old classic that is seen as a genre defining game because it is: Myst. Yes, it redefined the genre... in ways I fucking hated and that the adventure game genre took decades to fully recover from. It was a pompous mess in its presentation and was the worst kind of "doing action does vague thing or nothing at all, where is your hint book" puzzle gameplay wrapped in graphical hype which ages pretty poorly as far as appeal qualities go.
So many adventure games tried to be Myst afterward that the sheer budgetary costs and redundancy of the also-rans crashed the adventure game genre for years.
I know most people don't agree, but I never could get into Skyrim. I'm not much of a gamer, so I don't play a ton of games. I ended up playing Skyrim for the first time in 2021.
The story seemed generic to me, the combat was clunky, and the missions were all repetitive. I stopped playing after about 50 hours.
I should add that I love Fallout though. I'm not sure why I like it and not Skyrim.
Hard to feel how bad the combat is in Oblivion when you leave the sewers, dupe glitch some scrolls or potions to sell for enough money to bribe that glitched guy in Imperial City and then use the Lovers daily greater power to paralyze him and take infinite money out of his pocket and then save scum an Oblivion tower to get a Sigil stone that grants Chameleon and then using your infinite money to enchant 4 pieces of equipment with permanent 25% Chameleon and be completely undetectable no matter what forever
I was really into Mount & Blade when Skyrim came out and it still baffles me how one is by an indie dev and it follows the same very much video-game hitpoint / slash-through logic of melee combat but it pulls off the same thing so much better
I remember playing a little bit of Skyrim and then going back to oblivion. Oblivion is probably also shit, but the world felt much more alive. I was always curious to see what I would find when I left the paths, it was as if each area had a rich story going on. The gameplay wasn't very good, but it was made up for by some really cool quests.
Radiant quests ruined Bethesda games I guess.