What's your story for the aliens?

Once upon a time, a young woman from Oasis Springs discovered a green baby in a crater in the middle of the desert. She took it in despite not knowing what exactly it was, and shortly thereafter, the baby's father showed up at her door. He and his fellow astrounauts from Sixam had been observing the Earth for a while, trying to learn as much as they could about the life form on this - to them - foreign planet before attempting to communicate, but then, the powers that be decided to speed up the process by crashing one of their UFOs. So the woman took in the alien pilot, too, giving him an opportunity to find out more about her species first-hand, while she learned about his. The alien then signalled his colleagues that the planet was safe to land on.

Today, the woman and the alien are still living together, now as a couple raising the latter's daughter, who is all grown up. Oasis Springs has become the Earth's alien capital, so to speak, with one neighbourhood being inhabited exclusively by sims from other planets and their offspring. There is even yet another alien species that showed up shortly after the first one, the Asari (yes, the ones from Mass Effect if you are familiar with that game), who aren't actually aliens from a gameplay perspective, but blue-skinned, tentacle-headed spellcasters and vampires with alien powers added via cheat. I have yet to decide whether they're from the same planet as the green species, but yeah, that's the story of the aliens in my game so far.