Most players probably about the orginal(s?) challenge where you are suppose either name your children alphabetically or finding a spouse with same letter as your sim. But this one is not about going through 26 generation (or kids) alphabetically, what is, Im going to explain it right now.

1. Start out with how many founder families as you wish, BUT each founder family have to different first letter in their lastname, for example, A for Anderson, B for Bowler, C for Carter and so on.
You are not allowed to have several founder families starting with the same letter. So technically you can have 1 to 26 founder families, whether you want to play a legacy in an existing/custom hood where you focus only on one family or creating your own town will several different families (like the prosperity challenge for example) is up to you.

2. Every family member of these founder families has the same letter in their givenname as their lastname as well.
So for example, Andersen consist of 4 sims, mother Adam and Anna and their two children Adrian and Alice.

3. Choose whether the family (or families) are patriarch - their spouse take their husband lastname OR matriarch, the husband take their wife's lastname. Choose wisely! You are not alllowed to change this at any point of this challenge. You are however allowed to have different martial structure for the different families. I'll using patiarch families in the examples.

4. When your sims are getting married to another sim (townie, playable, npc, it doens't matter), they have to follow their martial structure rules.
Using Andersen as example, Adrian are never allowed to take his wife (wives) surname while Alice has to take her husband's.
Note: Even though you can't have several founders with same first letter, it's fine to marry other families with same first letter.

5. This doesn't sounds much of a challenge right? So What is the point of this challenge?

When your couple(s) is having kids, their kids has to take their same sex parent's first latter.
So let's say Alice married Billy Bowler, they had a girl and boy. The boy would take his father's first letter, B, like Brian while the daughter take her mother's, A, like Amanda. Since Im using patriarch as example, Brian will become the heir of the Bowler.

But what happen's if Brian couldn't father any sons. The game is over for this family, unless of course, Brian adopt a boy or have affairs that result in an boy OR Brian had a brother that could continue the bloodline. When there are no descendent with the correct matriarch structure left from the founders you started out with, the challenge is over. When tracing their family trees, All heirs will have same letter in their first and last name.

So I would reccomend starting with several founders or having one legacy family with several daughters or sons depending on whether your prefer patriarch or matriarch, or else.... hold your thumb that your families will have the correct gender for the childen.

IF you want to make it more challenging, you could have a theme for their names OR not allowed to repeat same names. Imaging a legacy family with Z or X. How far would you be able to go with this one? But this just optional though. There are no specific rules other than than you can't quit without saving and cannot break the rules mentioned above and I don't have any scoring system. (Im not good at numbers. ) I don't care if your motherload your families wealthy, use maxmotives or whatever, as long you don't quit without saving when something bad happens.

Sorry, I couldn't come up with an appropriate name for this take on the alphabet challenge. (Alphabetic heir apparent?) and I don't have any scoring system. (Im not good at numbers....) But hope anybody on here would like this version of the Alpabetic Challenge. Its not a generation challenge, but more about seeing how far you can go with your founder's bloodline and their martial customs (which I don't promote in real life btw) but has alphabetical flavor to it.