Yeah, it's that kind of suggestion again.
(also sorry the thread posted itself before I could be done writing it)
So, a while back, Tarn mentionned how difficult it is for him to code Half-elves into the game. But that made me think; "how about making Tarn's job even harder?".
So, in High-fantasy/Heroic-fantasy novels/media, there are a lot of "off-shoots" of different races that come to exist for a variety of reasons. Whether it be because of war and conflict, adaptation to a new magical (or non-magical) environment, selective "breeding" (I hate that term), curses, blessings, access to forbidden knowledge, creation of secret societies or shadow governments, or because humans thought elves were kinda hot that day. The necessary amount of those sub-races/off-shoots vary from people to people, but what if DF was able to generate such groups?
Now, you may ask why because there exist some form of balance in the game surrounding the primary races. My main argument being, well, flavor, but most importantly having to deal with different neighbors with their demands, needs, particularities and their own inner-politics. Elves disliking wood-cutting, humans being good allies to dwarfkind and goblins serving as the primary antagonists and Necromancers sometimes being powerful enough to make their own factions are good on their own, but imagine what could happen if mythgen could mess with them.
Let's say that, for example, some goblins reject their demonhood and decide to work for their own merit. The game randomly chooses a point in time and place that shall be used as the starting point of this sub-race, give it a random name synonymous with goblins, let's say, Hob-Goblin, and from there rearranges the "main goals" of the race. Whereas original goblins seek the total domination of the world to please their demonic overlords, Hob-Goblins could seek conquest as well, but also try to surpress the demon menace.
Another example would be ancestor races, essentially proto-off-shoots that justify the existence of the primary factions/races of the game. Dwarves for example could have very old ancestor, although much bigger and much sturdier than them, called "Elder Dwarves". Or given any sort of title.
To make these generated off-shoots unique, there should some sort of generated that gives them a twist when it comes to their appearance or behavior. Let's say the game generates a sub-race of dark elves who, instead of praising wood, praise jewels. From there, a randomizer could decide what kind of common physical or magical trait this sub-race could have. That, or the main actor that created those dark elves should have a significant influence when it comes to their appearance.
I think we could further with this, but it really depends on how far we'd want that randomizer to go.