Can I add Mods? Then Skyrim VR.

If I can’t, I’d choose a Game as a Service type of deal, if we could also make the assumption that the game would also be actively developed for the rest of my life.
Destiny 2 comes to mind, because I really love the lore and the gameplay.

If we can’t add mods or the game won’t be updated for the rest of my life, I’d still choose Destiny 2. After it gets cancelled, I’d just go outside and touch grass then, I guess. 😅

Age of Wonders 4, the sheer replayability of the game is bonkers. And they will only release more content as time goes on, both through DLCs, free content updates, and workshop mods.

Probably RimWorld. Somehow I’ve managed to accumulate nearly 4,000 hours. I’m pretty sure I could play for another 4,000 easily and then for the rest of my life. I love the stories that come out of each colony and how attached I get to pawns. I’ll never forget Dinkleberg, the troublesome cat that has nearly wiped my colony twice by leaving doors open for invaders then when out by snorting too much cocaine

With friends, it’d probably be World of Warcraft. I already have 20k+ hours in the game, and would likely play it even now, if Blizzard wasn’t just complete garbage right now.

Solo, a Diablo game I think, although I don’t know which. I haven’t played D4 (and won’t for a while, same reason as I mentioned above), I love the fast and fluid combat in D3, but D2 might have more variety.

Rimworld with mods. The shear amount of wild and bizarre experiences that I have in that game could easily keep me entertained for a lifetime. I doubt I’d get bored with it. Other than Stardew Valley and Zelda BOTW, it’s the only game I keep coming back to and unlike those two games, I don’t get bored of it. I simply have to tear myself away from it so I can function like a normal human being again.