Why don't they bring back the 'stealth attack' option? In the Japanese scenario (Sengoku: Civ3) there were Ninjas who could choose which unit in a stack to attack and were invisible to regular units (like subs). Another unit, the Yamabushi, was used to counter the Ninjas; they could 'see' the Ninjas and defend against them not matter how many units were on the stack, since they were not on the Ninjas list of units that it could 'stealth attack', they were attacked (when they were the best defenders of course).