Considering more traditional games, and discarding things like PUBG that popularized BR games...
I would say Dark Souls. The game that, coming from demon's Souls, created an entirely new genre and influenced several games, including big names like The witcher 3 and God of War. Dark Souls is the game of the decade, it will be remembered as the beginning of a genre that is becoming increasingly popular, possibly an immortal classic with tons of replay value.