You need to somehow end the game in 2 turns. Exiting the game does not count since that won't trigger the end game scoreboard.

The only way I found is to;
1. Pick Corinth (Difficulty or bonus does not matter).
2. Since you start with 1 trader use that to sell population to Sparta. Drag the slider for the 1 available ship and you should be getting -54 population at the start of your next turn.
3. Since your starting population is 40, you just gave away your entire village to Sparta, ending the game.
4. Restart the game since achievements only pop when you quit in this version.