Neither does this, but your original point is interesting. Capping stacks on ANY tile, but especially cities, would make the game play quite differently from how it does right now. It would nerf-counter units really hard though. Say the defender can have 4 units in his city. Which 4 does he choose? Horse archers are coming! Spears! Axes/swords! Defend with axes! But now what do you do against an assembled force of chariots and axes? Uh oh. Your axes are completely sitting ducks to chariots, so you need spears. But, spears are terrible vs axes. Anything less than 2 spears and a couple chariots will overpower the 1st one and you're a goner. But with 2 spears, it wouldn't take many axes to cut through. 4 archers? Might be the best bet after all, but then again 4 archers usually doesn't make any rusher cry, unless they're protective hill archers. The AI would be funny to watch in its current form though. I can just picture how one of my massed horse archer charges would look if the AI HAD to keep some of its units outside the city .