Maybe a crazy idea, but since all attempts to create a 3d rendering engine for freeciv have failed so far it could be feasible to run freeciv inside of 0AD?
There exists a HTML5/ JavaScript version of freeciv for running it in a web browser and 0AD has a full spidermonkey JavaScript implementation to run its AI and other scripts. Thus potentially a lot of work could be saved by combining the two?
Thoughts?