Maybe the the games could follow a similar path to the Civilization series of games, when in some of them the game ends when a nation builds a spaceship to Alpha Centauri.

I can imagine the game titles now:
Virtual Villagers 100: The Race to Space
Virtual Villagers 101: Isolans in Space
Virtual Villagers 102: Isolans on Alpha Centauri. laugh
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To err is human; to arr is pirate.