i'd assume

that you can only build workers and buildings as a non-army player. I don't really think it's in the spirit of the game to have one player control an army made from four players' stuff. It's more like using fed resources to tech fast, max fast, and then remax fast when necessary. as an economy player, you can totally do static D. you can totally get armor upgrades for your workers. That's pretty much what you can do combat wise.