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.
RDR 2 is like 3 or 4 great games rolled into one and all negating each other. The story is enjoyable enough with some depth and it's ruined by half of it being told through interactive cutscenes where you have to press W but if you don't magically follow the perfect path it fucks up the pacing.
It has a beautilly crafted open world with mechanics and side-activities, none of which do anything useful for the rest of it or have enough depth to stand on their own and a mission design that straight up fails you if you don't take the 1 path the developers want you to take.
It is a survival game, except set in the big rock candy mountains considering how much loot and money is just laying around.
It is so easy stumbling into money in RDR 2 that I had fully upgraded the camp before we moved to the second one, and I wasn't even grinding or anything, just hunting, fishing, looting, etc. like normal.
It was also frustrating to me just how cheap the guns are. It's trivial to get a fully upgraded set of weapons long before the end of the game, and the differences between them are minimal. You're given all of these options on how to deal with threats. You can sneak, you have throwing knives, a bow, you can lasso guys, you can make a sniper rifle. You have a wide toolbox. But honestly, you're given the most effective means of dealing with enemies very early in the game. Hide behind something, go into slow motion, and use a revolver. All the other stuff is just there to play around with and none of it ever seemed more effective than the basic revolvers. This is largely because of the lack of enemy variety. You have guys with pistols and guys with rifles who are further away, and that's really it. You're fighting the same exact enemies at the start of the game as by the end. I understand they were going for something grounded and realistic, but it made everything stale. The only time I remember being surprised by an enemy were the ones in the Epilogue who hide up in the branches of trees.
The differences between the horses seemed minimal as well.
At a certain point the only thing left to do was buying all the hats. With all that said, RDR 2 is a massive accomplishment. It's one of the very rare examples of good writing in a video game and it's surprisingly class conscious. The soundtrack is gorgeous too.