How do you design puzzle game levels with infinite replay value?

Question

A game like Tetris starts with no design, and this seems more amenable to infinite replay value than a level in Candy Crush Saga, for example.However, maybe there is a way to have a level with an initial design that also has infinite replay value?

tazu · Accepted Answer

This is a great question. There's probably some game-theory principles that could shed some light here, but I'm not well-read on it.