I was struck with the urge to play SMAC recently and couldn't get it to work properly. having fond memories of Maniac's planetfall mod, i downloaded the most recent version it and gave it a whirl. it was indeed as much fun as i remembered, but coming off of playing Civ V, it seemed cluttered and a little unweildy in places (but still marvelous nonetheless). I began to dwell on the idea of a Civ V AC mod, and what could be a fresh and interesting take as I've found the streamlining done in Civ V to be refreshing now that i've gotten used to it.
Resources: strip everything down to the basic AC resources: Nutrient, Mineral, and Energy. bases would then build facilities that consume these basic resources to produce secondary resources. this could even be pushed to tertiary and Quaternary resources, for both strategic and luxury resources. Luxury resources would be handled by 'wonders' that can be built multiple times, but increase cost exponentially if built by the same faction. I figure one could also have diminishing returns here as well. Natural features could provide more than one basic resource, or even secondary resources.
Research: add depth to the research tree without increasing the tech count: take a page from Master of Orion so that each tech will have multiple applications. further research can be done, or tech can be traded/found/bulbed or whatever.
Terrain: I really like the idea of the modular terrain that was done in planetfall, but i'm not the biggest fan of the map script. I would like to see tiles have the following qualities: Altitude, Rainfall, Rockiness, and Fungus, with 3-4 tiers for each quality.
that's all the notes i've got for now, but i do have some other ideas. i realize we don't have .dll access yet, but perhaps ducks can be put into rows in terms of concepts? comments/criticisms of my ideas