Kind of sounds like an AoK:TC scenerio I played once. I think it was called "King of Towers" or something. You had a whole bunch of towers, garrison the King in one, you'd get a whole bunch of units from your Castle, garrison him in another, you'd get other types of units. Still sounds like a cool idea, though.
You only played my scenario once? :p Anyway, I'm releasing a version for SWGB for my first SCN Punk project. It will be much more strategic than before. I got a demo out now. Download it here... King of Turrets Episode I Demo v2 (
http://swgb.heavengames.com/downloads/php/descpage.php?type=Multi&id=4) .