I picked my brain how to put up a catchy title, instead went to display ideas upfront.
Manned walls:
-Have them already on tier 2, both wooden and later stone. After all, manned walls were universal, common defense.
Towers should be able to be integrated into the manned wall, so that “castles” could be built.
Harbours:
-This large structure should come with coastal map. full third of the map being ocean, where villagers could fish. Volumes of fishing would be orders of magnitude higher than in lakes.
Trade would also be in much higher volume, but also in longer paces using the Harbour.
There would also be pirates who would attempt to raid Harbour from time to time.
Shipwright could be a building, crafting boats and ships.
Net weaver could also be made as a craft and a building.
Scorpio-towers:
-At the moment, the strong raiders are too strong, full armoured foes too strong. Catapults are save from retaliation and rams can move freely.
Not when the Scorpio-towers begin to sing their twanging songs.
They are larger towers with oversized crossbows. Scorpio easily reaches catapults, but has harder time hitting lightly armoured and nimble raiders.
P.S. Your game is very good and it has massive potential, diamond in the rough.