[Agema]

I kind of think that siege engines are abstracted into the breaking the gates routine. Siege engines were pretty rare until the medieval era: before then it was generally a lot of hard slog with the odd ballista. And there's already Iron Walls and Crumble.

I wouldn't mind maybe little upgrades: say paying another 100-200gold and getting towers that fire stuff that actually has a decent chance of damaging the besieging army. Say little 5-range flame strikes near the gate to represent boiling oil being poured out. But really, none of it is very crucial.