So' I've basically made a list of unique buildings that I want to implement. Whether these will realistically be able to be implemented, remains a question but I think I've been conservative enough with my ideas (and with the fact that I pretty much know now what can and can't be done in this game).
Let me know what you think!
PROPOSED UNIQUE BUILDINGS
Irrigation Lift ( I - III )
This would essentially be a unique building that you can place only on a river. It would give a solid amount of food and/or boost other farms in the area (don't know if this can be done yet).
Great Temple ( I - III )
Some sort of unique temple which also provides knowledge (and maybe some other bonuses if I can implement it).
2. IROQUOIS, LAKOTA
Casino ( VII - VIII )
You could build 1 of these per town and they would give an amount of wealth based on your current population (not sure about the latter, need to test).
City of Dreams ( VIII )
Essentially a major city that provides a huge amount of wealth (will try to make it go over commerce limit if possible). Costs knowledge to build and you can have only one.
4. PERSIA, NUBIANS
Advanced Oil Well/Platform ( VII - VIII )
Basically an oil well/platform that's capable of defending itself. Is much sturdier and can produce much more oil than normal oil wells/platforms.
Sea Outpost/AA gun ( VII - VIII )
An outpost or AA gun that you can place anywhere on water. Will also have some limited capability against naval units. Costs knowledge to discourage spamming.
Frontier Outpost ( VI - VIII )
A tower that you can place outside your nation's borders. They cost a bit of knowledge so as to discourage spamming. Not as effective as normal towers, but the ability to place them outside your borders makes them good enough I think (great for protecting trade roads or oil wells).
7. DUTCH, SPANISH
Colony ( V - VI )
A very small city that you can place outside your borders. Not nearly as strong as a normal city and doesn't upgrade, but can be used to extend your influence easier.
8. MAYA, INCA, AZTEC, INDIA
School ( I - VIII )
Similar to a university you can build one of these in each town to boost your knowledge production. The more scholars you have, the bigger the boost (need to try the latter).
Bantu Smelter ( VII - VIII )
A better smelter for the Bantu, that boosts metal production much further. It's also sturdier and can defend itself.
Elevated House ( I - IV )
A small defensible building which you can use to garrison your workers in if there's an incoming attack. The house cannot shoot back, but is hard to hit and provides a small amount of food. Cost a small bit of knowledge to discourage spamming.
Yurts ( I - VIII )
You can place one of these small groups of buildings per town. They boost your population cap (but not over maximum) and cost a small bit of knowledge.