This is one of my favorite prompts to work with because it leaves things WIDE open!!

"What if my current circumstances took xyz turn of events?"
"What if this dream I had were real? What would happen next?"
"What if I mashed these two cinematic universes together?"
"What if there were three of me?"
"What if I'd taken path B instead of path A? What might have transpired?"

The question of "What if?" opens us up to infinite possibilities for creative exploration and personal reflection. Anything can arise, anything at all, if you unleash your imagination upon "What if?"!!!

My most recent "What if?" idea:
"What if" there were an enormous generator hidden somewhere that created an energy field to allow aliens to look like us? "What if" that generator suddenly stopped working, thanks to some crazy kids or an unfortunate bird? "What if" some of the people we knew and loved suddenly didn't look the same anymore?

Oh baby, that opens things up for a lot of creativity, and perhaps some commentary on discrimination. ;)

"What if" there were good guys and bad guys on both sides? "What if" most of the aliens were just trying to live a peaceful life amongst us? "What if" some of them were trying to infiltrate our governments and militaries? "What if" some humans didn't care about intentions and were judgmental and even hostile simply because the aliens are different?

Disclaimer:
Just... please don't use it to dwell on the past. Lamenting with "What if I'd done such-and-such differently?" will get you nowhere you want to be.