How's about a generic Viking dude, with a lot of COB stuff that swaps out sets of arms / chests / helmets / weapons... so that we could have little hordes of dudes?
It would certainly be possible with lua, just not on a brick-by-brick scale.
units are expensive, so if we can improve one we already have lets do that. now we cant change the function of the unit, but we can make it better (example, we cant change our catapult, but we can give it treads). I'm thinking the following customizations would be possible:
weapons
propulsion
armor
other stats
In order to upgrade to the next tek level you must research it at your research lab. With 7 ages and 3 tek levels per age, there are 21 total tek levels, ranging from stone age to space age, as discussed earlier in this thread.
the only problem with this system is modeling and scripting the huge number of individual unit variations, but if done to a significant level it would allow for things like this but it would be pretty cool to see ships with rocket engines and doomsday lasers
of course the other option is to attempt to code a framework for classifying any creation rather than attempt to describe and give stats for every possible unit or structure, though at the moment i dont think this is possible
at this point its entirely up to what players want, a bunch of random units for specialized use like in most games or a few basic units with customizations