Zombie dice recently hit the shelves in my local game shop* If you're not familiar with it, it's a 'press your luck' type game where you play as zombies trying to eat humans. Keep rolling for delicious brains, but if you accumulate too many shotgun blasts, the humans kill you.
However, Steve Jackson recently posted his notes on the design of Zombie Dice (he recently did the same thing for Cthulhu Dice). It's an interesting insight into the process for fans or would-be designers of their own games.
In the case of Zombie Dice, it started out very similar to the finished product. But, when play-tested, it was pretty broken. Jackson then revamped the whole feel of the game with an almost, according to his description, board game like feel of various 'houses' and the ability to strengthen or weaken them. When that didn't work, he returned to his original idea and tweaked it until we got the game we have today.
Though I don't design games for a living (or even for a hobby, really), I guess I would take away that a designer shouldn't stay married to the original concept. Keep the theme and story, but be prepared to play around with it a lot. Any amateur (or professional) game designers have thoughts on his notes?
*Due to recent closures, "local" is a relative term in my neighborhood
