[This_Dude]

Sims 2. The best one. Although I don’t remember the alien baby

[Blue Highway]

I just looked it up and from my first search it says Sims4.

https://www.carls-sims-4-guide.com/lifestates/aliens.php#:~:text=In order to have a baby with alien,also invite Aliens to move in%2C of course.