mperial Rome is packed full of unique and interesting play concepts and new units: cataphracted cavalry, wagon laager forts, massed units of horse archers, light infantry tossing caltrops and more. Each of these concepts operates within the confines of the original system rules, with only slight modifications to reflect historical abilities and importance. So, rules-wise, if you own Commands & Colors: Ancients, you'll have no trouble learning the few new special rules.