The military unit concept is plain and unrealistic. New technologies always make the same predetermined units available - equal for all nations. The game has no worthy end. Nations can simply trade their technologies. The more nations share their techs, the faster they will advance in concert.
Outsiders fall behind.
All advanced nations share their technologies. There's no considerable scientific lead, no reward for being better. Maybe we'll have a big AI championship then and a strength rating system. Until then I give only a short introduction to the exchangeable AI modules, a speciality of the Civ Evolution Project. The Game Control does neither contain any AI algorithms nor any surface code.