I recall a Genetic Age mod for Warlords.
You'd research Ecology, and then you could research Terraforming. Not only could you change nearby tiles (good for combating Global Warming
) but you could research Sea Colonies.
You could build a Sea City using a Sea Settler and gather Methane or some kind of misspelled word of it and also some strange seaweed.
A Sea City came with a Biodome which could use a Methane Plant (no other city could as the Biodome was needed, which cities could not build) and made it look underwater.
Domination changed to 75% of the globe, not just land. Work boats could build underwater tunnels (like railroads) and mining facilities and sea farms and stuff
Sea cities were awesome, but they seemed to be too easily researched.
A city under the sea would be nice. How's this?
Sea Civilization
Capital: Bikini Bottom
Leader: Spongebob Squarepants (Funny, Annoying)
Squidward (Creative, Aggressive)
UU: Flying Dutchman (comes with Navigation 1 &2 and Drill I)
UB: Boating School (increase Naval unit experience by 5)
Their palace would be a pineapple, under the sea!