I'd like to suggest a slightly different direction. The phases already seem to represent increasing levels of population/organization. This could be expanded upon. Village -> Town -> City -> State As the civilization expands it allows greater specialization for individuals, due to economies of scale. Earlier phases offer a few general purpose units that, although they are versatile, are mediocre (or maybe even straight up bad), at everything. They shouldn't be able to counter anything, but should be easily countered by units in later phases (probably not until city phase, to avoid allowing the first person to reach town phase from effectively insta-winning). Something like: Village: - Citizens, crappy melee citizen soldier, crappy ranged citizen soldier, and a mounted scout. -- These are little more than conscripts using whatever weapons and armor they can get. Town: - Access to first professional cavalry units. -- These are the early elites of your society. It takes a certain level of organization and wealth to support a noble population, especially one that can afford their own arms, armor, and horses. - Ability to upgrade your crappy citizen soldiers to passable. -- now they get some training and equipment provided by the state, but are still basically conscripts. They shouldn't have quite the crippling weakness to the City phase professional soldiers that the crappy citizen soldiers have, but they'll still lose without a sufficient numbers advantage. - Access to several tech and service buildings; blacksmith, mill, etc. - Early defensive structures; wooden towers, palisades. City: - Access to professional soldiers. -- These are pure military units with no ability to do menial tasks. They should be much stronger than the citizen soldiers, and equally more expensive. - Some cavalry specialization. -- Horse Archers? Chariots? Light Cavalry that excel in harass tactics? - Fortress access (?) - Basic siege weapons - Heavier fortifications -- stone walls and towers - may want to introduce support units here -- something like priests in AoE 1/2 or Druids in R:TW State: - Upgraded professional soldiers. -- Badass++ Pay++. Should be a ridiculously hard counter to village citizen soldiers, and a hard counter to town CS. - Specialized infantry. -- Pole-arms for anti-cav, skirmishers, etc. - more specialized cavalry (?) -- I don't know what kind of specialized cavalry might have existed in ancient times New technologies should obviously be introduced as they progress. Not just another +1 to A/D, but more exotic bonuses (especially in the State phase) should be made available. Taking some inspiration from AoK, things like Murder Holes, Herbal Medicine, and Ballistics were great techs that went beyond a boring (but effective) +1 to X stat. One possible technology, which takes the theme of Generalist -> Specialist a step further, would be to make your citizen soldiers unable to build anymore in exchange for increased combat effectiveness. This tech would have to improve the Citizens as well (perhaps beyond giving them access to constructing military buildings). You could take it even further by removing the distinction between citizens and citizen-soldiers until a technology is researched that unlocks professional soldiers and "dedicated" laborers/engineers. The specialists would be much better at their jobs than the previous generalists. You could also have this tech automatically researched for certain civs that have a caste system in place. Lots of ways to go!