A web novel by John C. “Wildbow” McCrae.
I’ve read it fully (in russian) a while ago, and I haven’t felt that I’d like to reread it, personally I don’t like it very much as it’s pretty depressing
However it spawned a huge amount and variety of fanfiction which I absolutely do enjoy, and the setting is very interesting.
Has a sequel, Ward, which I haven’t read and not planning to.
Check out the entirety of Worm setting if you haven’t read it - wrote this for a friend.