Until you reach the Medieval Era, any city you found will kick off a new civilization that is initially a vassal of yours, complete with your advanced technology. Also, the algorithm favors civilizations of a similar art-style (if you are the Sumerians then you will found the Babylonians before founding the Dutch). Code Limitations: 1) In the game setup screen you must setup the MAX number of civs you want to appear in the game (I'd suggest filling all 18 slots). At Game Start, only the first 3 civs will settle in 4000 BC. Once all of the civs have been spawned, cities you found will be your own, even if you have not yet advanced to the Middle Ages. 2) Civs have the potential to be respawned if destroyed early enough, carrying with them the State of War (and probable vassal status) that they perished under. Concept Progression: Originally the idea was for "civilization" to start in 3 locations around the world (ex. MesoAmerica, Southwest Asia, Far East) and slowly these regions would be populated with future civs. Creating a vassal seemed like a decent way to balance creating a normal, integral city and creating an instant enemy. I don't often experience vassalage in-game, so I was surprised when after thousands of years these spawned civs would still choose to remain vassals. Ideally, they would declare their independence at some point. This did lead to massive, continental wars between other vassal "trees." Ideas or Suggestions? 1) Hard-code vassal separation OR make founding an enemy city somehow beneficial 2) Figure out how to erase a civ's memory if needed for re-spawning 3) Incorporate the 36-civ mods I've seen. (I tried to strip down one such mod and use their SDK myself... and failed) 4) Re-select civs & leaders in-game so that the next civ founded is from the correct part of the world (ex. a second China civ with a different leader) regardless of how that civ-slot was initialized at game start. Currently the game fits rather well into the One-City-Challenge concept, although that was not the intent.