I homebrewed a thing set on an alternate history future Earth where basically, there's an alternate history divergence with Jimmy Carter not losing reelection and then the US basically turning into a demsoc utopia resulting in world peace and sustainable prosperity, and then three different races of aliens show up. At first things go well with humanity, but then there's complications and tensions both between and within those three races, and the most advanced of the three ends up seeing humanity as a threat to them due to a bunch of other factors I introduced that would take way too long to explain and releasing a viral bioweapon that ended up killing most of humanity in the space of a year before a coalition of scientists and soldiers from all four species banded together to synthesize a cure and stop things. All of the game stuff happens well after, in the ruins of civilization, a la Fallout, but with a post-plague instead of post-nuclear aesthetic.
I have a whole novella detailing all of that lore on my Google Drive, most of which I wrote while unemployed in 2019. So you can imagine how weird 2020 was for me.
But that's on the backburner at the moment because my group is playing through the one with Gundren Rockseeker on the Sword Coast right now, with someone else DMing, because my mental health wasn't great in 2021 but we still wanted to play.