at least a long stories tnx.
https://storiesonline.net/s/56952/the-collapse-a-new-beginning-book-1 (and yes, there is a book 2)
https://storiesonline.net/s/43310/aftershock (localised apocalypse)
http://www.grynenbayritpublications.com/index/tales/aftershock/_default.html (the same story, re-edited)
There's also my Great Death series. The first book, Love and Death During the Great Death is strictly apocalyptic, while the sequels are all post-apocalyptic:
Love and Family During the Great Death
Grappling With Survival
Seeding Hope Among the Ashes
Note: The entire series is 'average guy faces the end of the world' and are not about doomsday preppers fighting others.
John Ringo's "Black Tide Rising" Series (5 books), Baen.
Try cmsix's "Nanovirus" story set. Many of his stories are incomplete but those are mainly finished.
There is a complete version available at the following link:
The original version is titled as such and complete. In my opinion it just illustrates how easy it is to reopen a finished story and add to it in online writing and publishing. Compare it with the version available on SOL to see the risks.
edited to add: The new material in the story should have been placed in a sequel not added to the original and left unfinished.
I hadn't realized that there was a difference between the SOL & the ASSTR versions. I first ran across it on ASSTR while it was being written.
At one time they were the same. But he came up with more ideas for the story. So instead of writing a sequel he reopens the story and adds to it after changing a few chapters in order to fit the new ideas. That as we all know now led to the dreaded incomplete status for the story. Of course there might have been other reasons, but since the original version won a couple of clit awards, draw your own conclusions. I have given up on mentioning my personal conclusions since according to experts. I am wrong.