When a good game designer is not a good player.
Let’s put a thing aside from the very beginning:
Every game out there is a problem solving experience, so puzzles are involve as a fundamental part of any game in existence. I wrote a post about that point a few weeks ago. On the other hand, it is common practice among game designers to create problems that can be solved in a number of different ways. When you play football there is a lot of possibilities at hand to score. Other games aren’t that open, but still offer a fair amount of freedom to the player.
The idea behind that is to avoid First Order Optimal Strategies (FOOS). Here there something about FOO’s (and related subjects) I posted months ago, but summarizing a FOOS is a strategy that represents the optimal way to solve the problem the game has to offer. If a FOOS exists, there is little the players can do to play the game in a different way, or in other words: as the problem has been solved, the game doesn’t have anything more to offer.
An excellent example is Tic-Tac-Toe as described by Raph Koster in his book A Theory of Fun. When you realize that any starting position have a very definitive answer in order to win, the game have nothing to offer from that very moment.