@Mr_NutterButter theoretically endless, but not in practice. you'll get bored of it long before you do and see everything that's possible in the game.

this is why community content is so important though if you're really aiming for a game that can be played long-term. the community will think up things pretty wildly different from the original vision of the game. it extends the game's life much farther and keeps people interested. this is why games like skyrim, and of course minecraft, have stayed relevant for so long, 11 years after their initial release.