And if we choose in barrack between alternate unit , for example Romans don't have archers, and include a research the research can be a pair between archers and cavalry ranged? Or have to select 2 champions units of 3.if you select 2 of them you can't select more. Is example elect possible pair of units. Archers or ranged. With Persian we have to choose better horse archer, and other unit. That is a idea. Research some tactic formations when we have battalions, or special guerrilla warfare tactics, like ability to do traps over ground. Or make decoys. And war invents like Archimedes of Syracuse. War medicine, training levels to have more fast and hp units. Something like ruthless Spartan training.