Plot:
It all began with two guys who shared an insatiable curiosity about the mysteries of the universe. They aimed to reshape their entire neighborhood into a thriving alien society... But whose offspring will be dominant in the neighborhood? The humans or the aliens?

Goal:
The goal of the challenge is to give birth to one male and one female alien baby, and make them marry. Populate the neighborhood with alien DNA as generations progress.

Neighborhood and mod (Mod is not necessary but recommended):

You must play in a neighborhood that has a number of Sims already living in the neighborhood.
I recommend playing with the Story progression mod. With the mod running, the neighborhood will live without your control and the Sims will continue with their generations. Which makes the game surprising and more fun.


Rules:
1. Create two male Sims. They have to be roommates.

2. The two Sims must have the 'Knowledge' Aspiration, as they both have a strong desire to get abducted.

3. Both Sims have to get a job in the Science Career.

4. Both Sims have to get abducted by aliens and grow their babies together. The goal is to have one baby boy and one baby girl.

5. In case the genders of the babies are the same, you will need to make one of them a townie when they are at least children, or make them move out when they adult.

6. Once you have two babies, boy and girl, and they are not siblings, they will inherit the house and marry each other in order to continue the generation.

7. Their life Aspiration is going to be Family and same for their future offspring.

8. In every generation you have to let a randomizer/dice to choose for you who is going to be the heir, to inherit the house.

9. You can decide who will leave the house and who will stay.

10. Play for several generations and discover which DNA is dominant in the neighborhood.


Happy simming!

Actually I've done that a number of times (sort of). It sounds like the kids from those first 2 babies have to marry humans?? Or can they also be abducted? In my game I have maybe 30 different PTs, so that would be a done deal. Also like to send teens to college -- and could make "alien" dormies. So if I play my way, yes - hood would become all alien. And if played with children of first couple only breeding with humans...um 50/50 chance of all aliens being gone?

You can plan this however you like. They can get abducted or marry a human.
But the whole goal is to breed out more aliens than humans, not creating them. The aliens have to blend in the neighborhood.

You can always make friends with humans in order for them to move in and get abducted. And then you can plan what to do with thr babie(s).