If I was never introduced to today's graphics, easily Morrowind. I would still pick Morrowind over Skyrim.
Gaming
You could readjust pretty easily within the span of the rest of your life.
Could probably be happy with Hades
Although if Halo MCC count as one game...
Path of Exile.
The Binding of Isaac: Repentance.
Pull up a chair and let me tell you about a little game called Nethack.
I've stopped playing it for years but if there is only 1 game I can play, it will be Dota2. In fact I stopped playing it because it took all of my time from other games
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.
Street Fighter 6. Hell, i know some who will only play that for a few years. FGC be damned.
Edit: Whoops, misread and thought it was for a year. I change my answer to Unity, lol.
Considering how many hours I’ve lost to FFXIV, I think that’s gonna be my choice!
League of Legends probably if we talk about video games.
Honestly, I already rotate through maybe 4-5 games. Skyrim or Minecraft could probably hold me over.
Doom/Doom II. Already been playing it for 3/4 of my life, and the modding community still keeps it fresh so even if the core game gets old, there's still things to do with it.