[Etaoin Shrdlu]

New idea, and one I just came up with (too late apparently?)...
Randomized opponents. You pick the number of other nations you want but not which ones. (while you could call for some at each difficulty level... say you wanted 8 opps at 4 normal and 4 hard)
Deadly themes would be excluded if any are around in the age being played (unless you let them in special). Super special option: No unveiling of the other nations' identities until 1) you meet them, 2) they get taken out by other opposing nations or 3) someone tosses up a global enchantment.