Just throwing this out for anyone who may want to use it. I'm also wanting to ask for any cool tips and ideas since I may turn this into a campaign. I'm keeping this vague as it is only a fresh idea I had today.
Mechanus is the plane of law and full of cogs working towards some unknown task or goal. It can be said that Mechanus is linked to nearly every ordered and precise thing in the multiverse. Much like each living thing in the world affects another, each cog within Mechanus changes the one next to it. What if some lives are linked to a single small gear within the limitless Mechanus? What would destroying that gear do? Pure chaos for you? Disconnection from the world you otherwise affected? Death?
My thought is that some authority figure has proven untouchable by any attempts to remove them to power. So the antagonists have set about trying to find the cog linked to this figure's life. This isn't an easy task and involves spying on the figure at all times to make sure that the suspected cog moves with changes in the figure's life. The adventurer's could get a start by being hired to root out spies which will slowly reveal the entire plot.
Of course the existence of the antagonists and experiments into how to destroy a cog should be causing disturbances within Mechanus. Therefore any adventures within Mechanus should be wraught with inquiries and suspicion for being outsiders during this time.
So, ideas? Has this been done before? Does this concept work with ideas already in place for Mechanus?
I think it works very very well actually - I've not seen it done elsewhere before either, so you're definitely onto a really good idea for a game. Law could use some more tie-ins with the metaphysics of the setting and this provides that very well.
Is your ruler's society going to be very lawful as a whole?