These are the rules that started it all. .
To begin The Legacy Challenge, enter any neighborhood you choose. This can be a Maxis-made one or a custom one. It does not matter how many other Sims live in that neighborhood. Create a blank 5X5 plot of land.
https://sims2challenges.blogspot.com/2007/04/episode-13-legacy-challenge-original_24.html
Original Date: Tuesday, April 24, 2007