I see that the creative mode is allows units from all groups and even region maps. I think it would be really fun if we had the option to simply enable costs, so buildings cost something and and tech requirements,so we couldn't build buildings without having the requisite tech, so we can try for the fun of seeing how different civilizations would tackle each resource problem and so on. Like using the united earth for ore and zolarg for aluminum. Basically it's just the main game without civilization limitations on what can be built. I imagine this would be easy to implement maybe even simply a new civilization that automatically tested true whenever the computer queries about what can and cannot be built by a given civilization. I've no idea ultimately without seeing the code but I think it should be a fairly easy to implement concept. Then much like it is now when you have the choice of how to start you just have above the creative mode a button with this type of mode.
i hope this gets added, as it would be pretty fun to play around with