Yeah, those are settings, heck, I'd love a Wild West themed city builder, don't need big stuff or cities, just give a lot of charachter and atmosphere, alternatively something similar to Colonization (Sid Meir), starting up towns and cities along the coastline and developing from there (tho that's a bit too similar to Clockwork Empires I think).
Anyways, I think what we need to agree upon is the general direction of the game and what are going to be the core gameplay elements. Everything else, including the setting is purely thematic and should be easily modifiable once we get the basics in. Stuff like different buildings and techs should be down to editing descriptions and models along with their corresponding modules that affect the gameplay itself.
While we're at it, production and processing, I think we could do something with agents (again not sure how or what exactly, not too versed into programming personally so this is just a general idea of how it could work). Buildings of all sorts (there could be special cases I think) could take in resources (in different manners, from the ground/nearby area, generated by itself, from transports) and under a set of conditions (powered, has workers, other factors like time of day or the weather) generates a number of resources per tick which are then sent off down the line to other stuff that needs it.
This would probably be pretty resource intensive but I'm guessing if we're focusing on the gameplay we could optimise this as much as we can while having the isometric graphics approach which wouldn't be so demanding.