Deus Ex designer Warren Spector has doled out what GamesIndustry.biz is calling the "Commandments of Game Design", though they're really just a bunch of design rules that he took to heart during the development of the excellent sci-fi FPS/RPG hybrid. I'll leave the commandments themselves to your link-in reading, but here's an excerpt from the article after the fact:
Every decision we made was filtered through questions implied by rules established right at the beginning of development. This list of commandments and addenda set a good course for the Deus Ex project and helped ensure that all of us stayed ON that course for the three or so years it took to go from concept to shipping game.
Why, you ask, am I telling you all this? Do I expect every game to adhere to the set of rules we established for Deus Ex? Absolutely not. Well, honestly, I wouldn't mind if every game followed these rules - that'd mean more games I want to play - but I know that's not realistic and probably not even desirable to anyone but me.
What I do know is that it's useful to have some set of rules, of some kind, for any game you pitch or work on before you spend months or years of your life (and someone's money) working on it.
Those rules, whatever they might be, must be relevant to your team, must be clear to whoever's giving you your development funds and maybe most important to players (though perhaps not explicitly in the last case). Commandments like these are your compass, your guiding star, the answers to all questions - even those that haven't asked or been asked yet.
But something came to me as I was thinking about these commandments and their continuing relevance to games regardless of scope, genre, delivery system or commercial expectations. I started thinking about whether I could usefully take the idea of commandments up a level? Could we talk about commandments for other games - in other words, for (Games) with a capital (G) - or even for the Games Industry as a whole?