Legacy challenge

A legacy challenge is a challenge created by Pinstar that challenges a player to play a family through 10 generations.

The player starts with one adult Sim by themselves in what is known as a "legacy lot" (a lot, usually 50x50 or 60x50, with only the bare necessities for the Sim). The use of cheats and who the family members can marry are strictly regulated. Every generation there is supposed to be an heir who keeps the legacy going.

The townie rule is different in The Sims 3, because everybody is from the same neighborhood.

Legacy Challenge links

 * Legacy Challenge for The Sims 3
 * Creator's blog
 * The official legacy challenge blog

Legacy Challenge Variations
There are many variations to the Legacy Challenge. Examples include:
 * Adoptacy: Sims cannot be born to the family, only adopted.
 * Alphabet Legacy: Naming the children in alphabetical order for 26 generations. The first generation names start with an 'A' like Alice, the second generation names with a 'B' like Bob, the third generation names with a 'C' like Charlie, and so on until the 26th generation names start with a 'Z'.
 * Cleanacy: Making it so the founder and every heir have 10 personality points in the neatness category/have the neat trait.
 * Dominant/Recessive Genes: Starting with a Sim who has totally dominant genes like a Sim with black hair and brown eyes, and seeing how long it takes for a totally recessive baby to be born like a Sim with red hair and gray eyes.
 * Fatacy: The founder, all heirs, and all spouses, must be fat.
 * Genacy: The number of children born each generation reflects which generation the family is in. The first generation would only have 1 child, the second generation would have 2 children, the third generation would have 3 children, etc.
 * Immortal: Keeping the founder alive while his/her family goes on for 10 generations, using the Life Fruit, Death Flowers and Ambrosia. Aging must be turned on.
 * Matriarch Legacy: The founder and all heirs must be females.
 * Patriarch Legacy: The founder and all heirs must be males.
 * Perfect Genetics: The founder must have an extraordinary hair and eye color like a Sims with white and pink hair with neon green eyes, and each following heir(ess) must have the founder's genes.
 * Prettacy: Starting with a very ugly Sim, then trying to make the prettiest Sim possible in 10 generations.
 * Rainbow Legacy: Making each generation represent a different color. The color and order is up to the player, so generation one could be pink, generation two could be red, and so on. The color of the generation can be reflected in the Sims' clothes, hair color, house, etc.
 * Random Legacy: Roll dice or use the Random Legacy Challenge App to randomly determine various gameplay elements of each generation of the legacy. Examples of gameplay elements are which job the heir gets, how many kids they have, and whether or not they can get married, among others.
 * Riskacy: Having the founder and heirs marry the first adult Sim of the opposite gender (playable, townie, or NPC) that walks onto the lot.
 * Supernatural Legacy: Each supernatural species must be present at least once in the family tree. For example, the founder could be human, but marries a witch, the second generation marries a werewolf, the third generation a vampire, etc.
 * Uglacy: Trying to create the ugliest Sim possible in 10 generations.
 * World Legacy: All heirs must be conceived with someone from another country.
 * Dilute Ugly Trait: Start off with as ugly a sim as possible, then try to completely dilute this gene in their following children.

In-game Challenges
Patch 12 for The Sims 4 introduced four achievements relating to the legacy challenge:
 * Legacy Player: playing a household as a normal legacy challenge.
 * Legacy Leader: playing ten households as a normal legacy challenge
 * Alphabet Legacy: playing a household for 26 generations. Unlike the aforementioned Alphabet Legacy, naming the descendants in alphabetical order may not be necessary to complete this achievement.
 * Legendary Legacy: playing a household for 100 generations.

Other Challenge links

 * TheSimsResource.com List of ChallengesThe Sims 3 Apocalypse Challenge - old site
 * The Sims 3 Apocalypse Challenge - new site
 * The Random Legacy Challenge
 * Sims 4 Achievements