It is and afaik always has been available for free
For years I made book versions of the articles on my website. When came time to make the third volume, Amazon threw a massive fit that my books were reusing content!
I ended up abandoning their bookmaking service for Lulu. My books are still for sale on Amazon, but I’m not letting them do anything with the printing.
I ran into this with my first book on Amazon maybe a decade ago. I reused/refined a lot of my blog content as well as some material I published elsewhere. But I sent a bunch of links to show that it was my byline and didn't have any issue going forward.
Oh got it. Thanks!
It's still free on itch.io
It also made front page on HN a while back, maybe 6 months ago?