Dragon's Dogma 2, getting close to 80 hours. I still feel like I've only scratched the surface because, now that I'm getting 60'ish level pawns to run in my party, I'm still finding a ton of secrets in areas I've already explored extensively. In the game, the pawns you summon can show you secrets about the world that their players have discovered. It's a neat mechanic.

If you like exploring open worlds, it's a pretty great game.