Honestly, it's hard to say, since I think I'd get tired of just about anything if I did it for too long/without any changes. Zelda Breath of the Wild and Tears of the Kingdom are pretty close to me (and I played the former on/off for like 5 years), and I'll always probably be able to play a multiplayer game like Mario Kart 8 Deluxe, but a bit of variety will always be necessary.