I agree with
this.
It makes me think about games.
Are all games changeable? Basketball, foosball, chess, Angry Birds, chicken, roulette, Russian roulette, investing, sudoku, riddles, poetry? I can't think of any that aren't. There often is (and probably should be) a rigidity somewhere at or close to the core of the game. But rules can change. Stakes can change. Players' attitudes can change. A single game can become part of a triathlon, a decathlon, an Olympics.
But some games embrace changes more gracefully than others. And I think those games are the most fun, the most obviously infinite.