Preparing to play Diaspora tomorrow night has me thinking about sub-systems.
I had conversations with Luke a long time ago about BW’s sub-systems. Burning Wheel has Fight!, Duel of Wits and Range & Cover as concrete sub-systems. You can keep all of the other pieces intact (Circles, Resources, Bloody vs.) and change that to Lyrical Poetry, Jousting and Laying Seige for Arthurian flavah. Or you could go with Pillaging, Kinslaying and Boasting for a kind of viking epic.
IMing with Joshua got me thinking about social combat for D&D. What if there was a system that existed outside of classes. All of your bonus was via social class, as described by a set of clearly defined set of parameters the GM had. Social class was how you got your social hit points and social armor class. Yes, you could kill the entire king and his court. You are a 20th level fighter but he will destroy you socially. Will you use your dungeon-made power to destroy those who beat you socially?
So, yeah, thinking about sub-systems is all.