^ that's what i was going to say. For much of its history, game design was taking one simple model and repeating it over and over again in a different context. In essence, that's what computer programming is. For example, calculators perform all of their functions by using only addition in different ways and combinations.

Eventually after enough times any game will become boring, but even the simplest things can be fun for a long time. Counter-Strike, since I brought it up in another thread, is one such example.