Unicorn Western 2 is also the second book to be co-authored by the independently published duo. As a sequel to the original Unicorn Western, it continues the story of gunslinger Clint Guilliver and his talking unicorn Edward as they pursue the dark rider Dharma Kold.
"We decided to write Unicorn Western when my usual writing partner David Wright challenged me to write a Western without doing any research," Platt said.
"He didn't think it was possible, and he believed my knowledge of history is so poor he joked that I'd probably put unicorns into the story.
"From that joke, Unicorn Western was born. It's early days, but so far the buzz around it has been fantastic. Johnny and I are now planning a series of nine novellas minimum."
First launched in December 2012, the Unicorn Western series has already notched up 10 five star reviews on Amazon and Amazon UK, and has an average review score of 4.7 stars out of a possible five.
When they're not forging new genres, Platt and Truant- together with David Wright - give writers the inside scoop on indie publishing in their weekly Self Publishing Podcast.
"Like all my fiction, Unicorn Western is indie published," Truant said. "I'm part of a new generation of authors who developed our voice and a loyal following of readers through blogging. It makes sense to us that you don't need a printing press or a publisher to get in front of readers. All it takes is the click of a mouse, quality writing and a touch of marketing savvy."
Platt added that readers no longer shun self-published books like they used to.
"Self-published books used to be pretty much ignored. Publishing your own book was seen as vain, and few readers wanted to risk their hard-earned money on a book that hadn't met the standards of a publishing house.
"Amazon's review system makes it far easier for readers to find quality self-published books. Fifteen of Amazon's top 100 bestselling ebooks in 2012 were self-published, which shows how much has changed in just a few years. The stigma of self publishing has been annihilated.
"Now, all smart authors want to self publish. With a typical royalty rate of 70%, compared to 15% from traditional publishers, going indie is the future of publishing."
Unicorn Western 2 is available from Amazon.com priced $2.99.