Five years ago, I ran an experiment to see if I could generate passive income by selling Sudoku puzzle books on KDP – with zero ads.
Using Book Publisher Tools, I created and uploaded two variations of Sudoku puzzle books, the books created used low-competition, natural keyword-based titles – “Alphabet Sudoku” and “Wordoku – Cat Sudoku.” At the time, competition was lower than it is now, allowing my books to rank high organically within the Amazon search.
I wanted to see whether it was possible to generate passive income with minimal effort and no marketing. Over time, I discovered that by scaling up, it’s possible to earn $36,000+ per year, even without a marketing budget. Here’s exactly how I did it – and how you can too!
The Results?
- Zero marketing. I did no advertising, no social media promotion, and no paid campaigns.
- Steady trickle of passive sales. Over five years (which I used to gauge a better set of results), these books have generated approximately $180.00 – equivalent to about $36 per year for two book variations.
- Sales dwindled further over time. As more books entered the market, my sales gradually decreased. Without ongoing promotion, it became clear that relying on organic search rankings alone was not a sustainable long-term strategy, however, the odd sale still comes in every now and again.
- Declining rankings over time. Some books gradually fell in rankings as competition increased and more books were added with similar keywords.
- Performance Across Volumes. I created 5 volumes of Alphabet Sudoku and 2 volumes of Wordoku – Cat Sudoku, totaling 7 volumes (these are essentially the same book, just with slightly different covers – to differentiate these you could call them a different Volume number and change the main cover colour to a different one – and a change of puzzles internally which the software can produce very quickly). Out of these, only one volume from each type received no ratings. Considering that I sold only around 100 books over five years, this is not a bad result. In total, I received 9 ratings across all volumes, which suggests a decent engagement rate relative to the number of books sold (9%).
What This Taught Me About KDP Publishing
My experience highlighted the fact that simply uploading a book and leaving it to rank naturally can work – but it has limitations. Relying on Amazon’s search algorithm means that books can eventually get buried under an avalanche of new releases. Without active marketing, sales dwindle over time.
However, this also presents an opportunity. If a book can generate sales without any effort, imagine what it could do with consistent traffic and promotion!
How You Can Scale This Model
While my experiment showed that books could still generate sales with no marketing, the real opportunity lies in scaling up and actively driving traffic. Here are some strategies to take this simple KDP model and turn it into a serious income stream:
- Increase Visibility with Marketing
Instead of relying solely on Amazon search traffic, leverage paid and free marketing methods to boost sales:
- Paid Methods:
- Invest in Amazon Ads to increase visibility for your book in Amazon search results.
- Use Facebook Ads targeting puzzle lovers, parents, educators, and retirees who enjoy brain games.
- Try Google Ads with keywords like “fun Sudoku puzzles for beginners” to capture search intent.
- Free Methods:
- Use Pinterest to create visually appealing pins showcasing sample puzzles and linking to your book.
- Leverage TikTok and Instagram Reels to show snippets of Sudoku-solving tips and promote your books.
- Start a YouTube channel dedicated to puzzle-solving, where you subtly promote your books in the videos.
- Blog about puzzles and SEO-optimize your posts to attract Google traffic.
- Publish More Books and Dominate Your Niche
One of the easiest ways to increase earnings is to publish multiple books and create a brand within the puzzle book niche (or another niche). The more books “buy buttons” you have out there, the more sales you’re going to get.
- Multiple Variations – Instead of stopping at two books, scale up by publishing multiple variations – different difficulty levels, unique themes (e.g., “Dog Sudoku,” “Christmas Sudoku”), and different formats (activity books, printable PDFs).
- Bundle books into collections (e.g., “The Ultimate Sudoku Pack” with multiple difficulty levels).
- Experiment with different niches – not just Sudoku but also word searches, mazes, crosswords, and brain games. Again, you can create these easily using Book Publisher Tools, which provides software to generate different types of puzzles quickly.
- Personalization – consider offering personalized Sudoku books, where customers can submit specific details (say a name) and receive a customized puzzle book with their details integrated into the design. Another unique suggestion would be to create personalized puzzle books for a couple getting married to distribute to the congregation at their wedding or for someone’s birthday party…
To put it into perspective – if two book variations are generating $36 per year with no marketing in a low-competition keyword niche, that equates to $18 per year per book variant. Now imagine scaling up to 2,000 book variations (you don’t necessarily need to create variants – * I only did this to see if the sales would increase by adding more variants, which I didn’t see happening – it might be different if sales were going really well for an individual title) – that would be a potential $36,000 per year. And the best part? With the right software like BookPublisherTools.com and some time commitment, this is entirely achievable. Create them once, then sell them repeatedly…
* All the same book variants for sale came up in the returned results list from using the Amazon search bar
If you could theoretically generate this kind of income with 2,000 book title variants and no marketing, imagine what you could earn if you had a website (which you can now start for FREE with the likes of Groove.cm or Systeme.io) to drive even more traffic and sales.
- Create a Standalone Website for Your Books
Instead of just depending on Amazon, build your own platform to gain more control over your audience.
- Develop a simple website listing all your books with direct links to purchase them on Amazon.
- Use SEO-friendly blogging to attract organic visitors interested in puzzles.
- Offer bonus downloadable puzzles as an incentive for people to sign up for your email list.
- Include an author bio page to build credibility and connect with puzzle lovers.
- Monetize Beyond Amazon with Digital Downloads & Memberships
Once you have an audience, expand beyond Amazon:
- Offer printable puzzle downloads on your website (sell individually or in bundles).
- Create a monthly membership where subscribers receive fresh puzzle packs every month.
- Sell PLR (Private Label Rights) Sudoku packs to other creators looking to sell puzzles under their own branding.
- Develop Sudoku challenge books that engage users to complete a puzzle series over time, potentially creating a more interactive experience.
Final Thoughts
This experiment proved that even with zero marketing, puzzle books can generate passive income. However, the real potential lies in scaling up, driving traffic, and expanding monetization methods beyond Amazon.
If you’re interested in trying this, start small, use creative niche keywords, and implement a marketing plan from day one. As you build a catalogue of books, you’ll develop an ever-growing passive income stream with the potential to turn it into a full-time publishing business!
Ready to get started? … Remember the proverb “from small acorns mighty oaks grow”