I wanted to write Voidstone Chronicles in the Pocketmod format; 8 pages of concise game rules. But it just isn't working for me.
So, I'm amending my plans. I'm now tossing up whether to use a full book, or a series of pocketmods to cover various aspects of the system (one for character generation, one for adventuring, one for combat, one for magic, etc).
It probably doesn't help that I've also produced 20 pages of illustrations for the setting so far.