For me, it’s Breath of the Wild.
I’ve enjoyed a great many games in recent years but it’s probably been almost a decade since I played a game that moved on single player gaming in some way, like RE4, Metroid Prime, Mario Galaxy or GTA Vice City.
BOTW for me has changed games forever. There are things about it which I don’t think are perfect (lack of difference in weapon durability, enemy variety and larger dungeon-esque shrines), but an iterative tweak to these issues seems very easy in a future follow up.
It’s not just the faith it places on you as a gamer, or the freedom; rather the way it removes the limitations of open world games entirely: Climb anything. Weather that has a genuine effect. A story that plays out cleverly no matter your path through the game. 100s of reasons to play on after the credits roll. Items that affect your experience rather than give you XP. Mechanics and systems that you’re given to play with from the outset, meaning anything that you can’t do in the game is purely of your own shortcoming.
I don’t think I’ve ever spent so many hours in a game just happily doing… well, nothing, really? Just climbing a peak to see what up there and watch the sun come up.
BOTW is s special game for me and one which I think has changed open world adventures, for the better, forever.