Like many authors, Andy Weir, a computer programmer, could not get an agent interested in his novel, The Martian. Weir, the son of a particle physicist father and an electrical engineer mother, spent years researching orbital mechanics, conditions on Mars, the history of manned spaceflight, and botany in order to write his survival story about a man marooned on Mars. While clearly a work of fiction, Weir, to use his own words, "scienced the shit out of it." The novel is laden with enough math and science to defend his premise, which is that a man can survive alone on Mars.
The plot of the book (and film) is fairly straightforward. Astronaut Mark Watney is lost and presumed dead when a manned mission to Mars is hit by an intense storm. Abandoned by the rest of the crew, and unable to contact NASA, Watney uses his knowledge as a botanist to grow food in the mission's artificial habitat. He figures he'll need to survive for at least three years. (Think Cast Away, but without the volleyball.) Eventually, Watney locates an old probe and uses it to regain contact with Earth. The rest of the plot follows the twists and turns of various disasters, recoveries, and attempts to rescue Watney.
Since Robinson Crusoe, survival plots have been sure-fire hits among readers. There is something deeply engaging about an individual's fight for survival. I believe this is because it is a theme we can all identify with, and, at a metaphorical level, it is one we all experience. Yet, this story was rejected by every agent Weir contacted, probably because of all the science. Science and math are not considered "marketable." (Neither are long sentences and words containing more than two syllables.)
So, how did Weir manage to find an audience?
First, Weir posted his book, chapter by chapter, in serial form on his website. Then he published it on Amazon for 99 cents. After the book had gotten 35,000 downloads in less than three months, Weir was contacted by Crown and offered a contract. The rest is history.
If this story seems pie-in-the-sky to you, it is. In fact, it's a little like the hilarious Monty Python skit, "How to do it."
"This week on 'How to Do It' we're going to learn how to play the flute, how to split the atom, how to construct box girder bridges and how to irrigate the Sahara and make vast new areas cultivatable, but first, here's Jackie to tell you how to rid the world of all known diseases!"
So, to paraphrase Monty Python, all you have to do is "write something marvelous, and when the world starts to take notice of you, you can jolly well write your own ticket." (Sadly, this is a commonly held delusion among young writers.)
To answer the question "How could Weir's story possibly be true?" I consulted with someone I gave birth to (Spawnling #2). I figured he could give me an insider's view of how on earth someone can end up with a movie deal after posting a novel on his website. After all, there are a billion websites out there. How did readers find his?
The answer, not too surprisingly, was to get onto a bigger platform. Spawnling #2 described reading a serialized book on a website after encountering it on Reddit (/r/books, to be precise). Reddit has a much deeper reach than most individual websites can muster. By garnering attention on Reddit, lots of people began talking about the book, and it gained a readership. (Go here for other writing-related sub-reddits.)
You may be tearing your hair out right now, wondering how your historical romance can possibly appeal to a bunch of 20-something males on the west coast. (That's Reddit's demographic.) The truth is, it probably won't. But there is always a platform (meaning a popular site) for the sort of people who will want to talk about your book. It is up to you to find where your demographic hangs out, and how to reach them.
I've made your job a little easier by assembling these resources:
Top 5 Sites for Science Fiction Writers
Top 5 Sites For Mystery/Thriller Writers
Top 6 Sites for Romance Writers
Top 5 Online Resources for Children's and YA Book Writers
Top 5 Sites for Historical Fiction