The only game I could stand to play for eternity with no sequals, mods, or expansion packs?
Then I'm sorry to say it's a casual game called Fairway Solitaire. XD It should bore the snot out of me, but it's got the type of cocaine-like addiction this one gaming magazine guy had with Peggle.
If expansions & mods are allowed, the Neverwitnter Nights. If sequals are allowed, than Baldur's Gate. Te first game has content that goes on forever, the 2ed is funny & you can change it a bit each time.[/quote
You can play Expansions, mods, but only one game, and its only for one year not an eternity. That would be torture.