Before we even think about new unit types, we need to balance the current types. So far the entire combat system is basically this... Spam archers-upgrade to composite bowmen, include 1-2 horsemen for taking cities. Any other strategy is ineffective and will fall prey to the above strategy. Then over the course of the game, you would head towards crossbows. If you haven't won by then, head towards artillery, then towards great war bombers. Upgrade GWBs to Bombers and you should have won the game by now. Naval wise, you pretty much ignore triremes because as melee units they have to die to even stand a chance at taking a city since only so few can attack per turn compared to range. Galleys are also pretty worthless unless you head towards them right away. So naval wise, it is all about getting Frigates/Privateers then upgrading them if its required too. One note to mention here is Ironclads are worthless for attacking because they take forever to travel the ocean for whatever reason. Then besides the standard units, you may change up the same old combat strategy provided the Unique unit of the faction your playing is good (Horse Archers, Keshiks). So before we even think about adding anti-infantry and ranged cavalry as standard unit lines we need to fix the current balance system so range units aren't totally dominating it. Basically players should be building balanced armies (provided they have the resources) such as 4 swordsmen, 3 spearmen, 3 composite bows, 2 horsemen instead of 8 composite bows, 2 horsemen. Best way to bring down range units is to add a ammunition system to them while making them do less damage to damaged units, and also slightly decreasing their strength. Historically archers were used to thin out the enemy ranks so the melee soldiers could get in and finish the job with less deaths. When engaged in melee, they get slaughtered, especially by cavalry. Also fighters,anti-air units, triremes need to be looked at as currently they are useless entirely.