Looks like Fish Farms and Satellite Dishes are the new improvements, in
far right bottom and far center top respectively. And I feel very confident that that big science-y construct is the
Amundsen–Scott South Pole Station. The building shapes and dome are too spot on to be anything else.
It's hard to tell what the new resources are. But one is almost definitely Palm Oil,
seen here top right corner. I'm seeing also what looks like gold in
bottom right here. Very plausible since this is already available in some scenarios. Third could be whatever that white stuff is
here at far left, next to the commerce district? Though those buildings (esp that cross-looking one) typically only show up in a district, so that could be not an improved resource but our 2nd mystery district!
Regarding the Boardwalk/Entertainment District, is it possible that a heavily upgraded Governor could provide the ability to build districts on the water? Since promoted Governors is meant to be useful for "tall" cities, that would make a lot of sense. I've thought about this before the announcement, as cities like Boston heavily expanded their square mileage by building out into the ocean.
Will be excited to see what else we can sleuth out.
