Why cant there be more types of units even adding buildings. A cleric that has bless and cure wounds or cure ailments like poison with a church you research better spells. A troll you could buy with gold dragon coins that has regeneration. Maybe an alchemist that you can increase weapon and armor bonuses overall or get flaming arrows for archers that increase building damage or research a better shield to increase arrow protection for infantry. Maybe a dwarf barracks that you can buy dwarfs that have the protection in melee instead of arrows like the infantry even at higher level maybe dwarven pig riders and ax or hammer throwers that have less range but more damage to buildings. Give more variety because the game is getting a little stale. Better tower options or have the citadel be up gradable to firer arrows. Maybe even have some aerial units of some sort like birds, wyverns or drakes. But the new upgrade was cool so way to go on that.