Probably Rimworld. With the storytelling aspect, each playthrough feels like a different experience.

Rocket league. I know some people consider it the same thing over and over, but to me it plays like a sport. Every match is different, I've been playing almost daily since the pandemic, which is when I got into it. And apparently I'm in the top 5% of players. Which just shows how much the game clicked with me

I'd go with "Hide the Sausage".

Let's see how Starfield turns out to be. If it is any good, it will entertain me for thousands of hours and if it has good mod support, why not commit for it for the rest of my days? Still a lot of ifs tho

I would love to say Crusader Kings, but it's probably chess.

I have about ~9,000 hours logged in Skyrim over the last twelve years thanks to mods, and I'm sure I'm not done. So I'll stick with that.

Age of Empires 2. I am playing it for 24 years already, so why not 50 more?

Cribbage, mainly because I like calling out 'one for his knob '.

Minecraft with mods definetly - really adds a lot of variety, and even though I take long breaks i've been playing it a ridiculous amount of time since early beta maybe 11 or so years ago.

The Mass Effect trilogy (I consider it one game) - no matter how many times I play it, it still feels fresh.

Probably Diablo 2 LoD. Best ARPG ever made.

Skyrim with mods, honestly. I feel like there's a lot of potential there

Elite Dangerous, assuming the servers would stay up I have an entire galaxy to explore

Rocket League

And I'm gonna hate the rest of my life

Minecraft. Mods are like magic, and can totally change the game. I've lost countless hours just poking around and building fun things, even on vanilla.

Chess

Elden Ring is a contender for sure

For me it's Assetto Corsa (modded, in VR). Most-immersive, addictive, exciting gaming experience possible, in my opinion. I did thousands of miles on the Tokyo interstate at night alone, just trying out different cars. Sometimes raining. Sometimes not. Listen to music while you drive/race. Really amazing.

Minecraft, while nothing particularly special to me, is most likely what I would choose. The potential for making your own fun in that game is ridiculous even if its been the victim of bad new mechanics bloating vanilla for the past decade. Even the longest of my favorite games cap out around 200-300 hours with all their content squeezed out of them, and with the amount of gaming I do on the regular thats gonna last me a few months at best.

Nethack. But definitely not in vr.

Single player - F-Zero GX. The skill cap in this game is astronomical - mastering it akin to mastering a musical instrument. There's nothing else quite like it.

Multiplayer - Smash Ultimate. The amount of unique character matchups and interactions is so massive that there's always something new to see.

Dark Souls remastered

Honestly, yeah. If I'm allowed Mods, then the roof is just the level of my creativity. If I'm only allowed one game, it's a damned good one.

I would probably say morrowind with all the community mods and modern engine.

TheoTown, it's such an underrated mobile game and i would love to just play it for the rest of my life

If I was never introduced to today's graphics, easily Morrowind. I would still pick Morrowind over Skyrim.

For me, it would definitely be Red Dead Redemption 2. I've played the main story several times now and will probably soon start over again.

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.

Is multiplayer allowed? If so, probably Dota 2. For single player, Factorio.

Path of Exile.

At this point, I think I might have to go for monster hunter. Or Dragon's Dogma. Just some kind of super deep action RPG would do it.

Skyrim

In fact, this is the only game that I have played for the last 6 months lol

Could probably be happy with Hades

Although if Halo MCC count as one game...