Developer Mark Ffrench of Divide the Plunder offers insight into his Mosaic puzzle games following the release of his latest entry, Mosaic of the Strange.

*Mosaic of the Strange*. Credit: Divide the Plunder

I’ve played several of solo developer Mark Ffrench’s excellent Mosaic puzzle games and previously reviewed Proverbs. When I heard he was releasing a new game in the series—one that adds a narrative spin to the established formula—I was immediately intrigued. It felt like the perfect opportunity to sit down with Mark and learn more about both the series and his design process.

The Mosaic games blend logic-puzzle ideas from Minesweeper and Picross across enormous canvases. In Proverbs, for example, players tackle a massive grid of more than 54,000 tiles. Scattered throughout the board are numbered clues from 0 to 9, each indicating how many tiles in the surrounding 3×3 area should be painted. Completing the oddly shaped regions outlined on the grid gradually reveals sections of a larger image.

The latest series entry, Mosaic of the Strange, is themed around paranormal mysteries, with each completed puzzle unlocking details about a strange incident. Unlike the earlier games, this one also has a narrative: a murder mystery in which two FBI agents investigate a strange crime. Each puzzle reveals a clue that advances the story.

This latest installment also introduces difficulty options that adjust how many advanced deductions the puzzles require. While earlier Mosaic games often put me into a flow state where I could meditatively find solutions, the higher difficulty modes in Mosaic of the Strange regularly stumped me. As always, every puzzle can be solved purely through logic, but the higher difficulty modes demand deeper focus and more complex reasoning. A new hint system supports these tougher puzzles by teaching deduction techniques rather than simply revealing answers, using highlights and explanations to guide players toward solutions. “Give a man a fish, teach a man to fish,” and all that. It’s a great idea, and I’m not sure that I’ve seen puzzle hints executed this way before.

I loved Mosaic of the Strange and can’t recommend it highly enough. Talking with Mark only deepened my appreciation for the entire Mosaic series. The interview below has been lightly edited for clarity.

Mosaic of the Strange is available now on Steam.

Sam Kahn, for The Geekly Grind (GG): Could you introduce yourself? Tell us who you are, your company, and what you do.

Mark Ffrench (MF): My name's Mark Ffrench, I'm a solo developer of puzzle games, and Divide the Plunder is my studio name, but the games are all created by me and a few contractors that I work with.

GG: Can you describe your journey into game development? How do you balance your work as a solo dev with Divide the Plunder and your job as Lead Engineer at Marmalade Games Studio?

MF: I've been tinkering with game development since I was a kid, creating games in BASIC on the Spectrum 128k, and then Klik & Play, DarkBASIC, Flash, XNA, and finally Unity. One of my teachers at secondary school was also able to secure me a work experience placement at Lionhead Studios, playtesting Black & White, which was awesome and convinced me that the games industry would be an amazing place to work. But, I never really took it really seriously as a career path until after studying Biochemistry at university, when I ended up stuck in a fairly boring science publishing job. I started learning how to code again, and spent weekends taking part in game jams like Ludum Dare and 7DFPS, and it was by chatting with fellow game jam devs that I was able to get my first game development interview and role at Firefly Studios (creators of the Stronghold series) back in 2012.

I spent around 13 years as a Unity Developer at a variety of studios, mostly on mobile games, ending up as a Lead Engineer on F1 Clash (at Hutch), then later Ticket to Ride (at Marmalade Game Studio). I actually left Marmalade in August last year, by which point I'd built and released Mega Mosaic, Proverbs, 2024: Mosaic Retrospective, and Mosaic of the Pharaohs by working on them in evenings and weekends.

GG: How do you approach solo projects compared to development with a larger team? How do you manage wearing all the hats—technical, artistic, and design—while working solo? Was there a learning process?

MF: There absolutely was a learning process, and this is actually my second attempt at going solo. Back in 2021, I quit my job and gave solo development a try for 6 months, working on an early version of Logic Town, but I spent all that time going round in circles trying to make it work as a free-to-play mobile game, changing themes, prototyping and throwing away designs, and trying to create all the art assets myself. I completely failed to ship the game in that time, burned through a load of savings, and then had to go back to a full-time job, which was really disappointing. But I was determined to finish it, even if I now had to do so by finding time late at night and at weekends.

I decided to turn it from an F2P mobile game into a premium PC game. This change made the game a million times better, and the project much simpler to build. I also outsourced all of the 2D and 3D art to some really fantastic artists and finally managed to get it finished and shipped in 2023. The game is popular and performed fairly well, but I'd spent so much time working on it that my hourly wage for the project was fairly low.

The lessons learned were to keep the projects simple, to know exactly what I'm creating from the outset, to finish the projects quickly, and to make sure that I can outsource significant chunks of content creation so I don't get burnt out. By the time I left Marmalade 2 years later, I'd shipped 4 DLC packs for Logic Town and 4 Mosaic games, all built in my spare time.

GG: Tell us about your mosaic games in your own words - what kind of experience are you trying to create with these enormous puzzles?

MF: It's quite similar to the experience of solving a big jigsaw puzzle. I miss being able to slowly see a picture come together over a weekend (currently, my young kids would almost certainly charge in and trash the WIP jigsaw). After all the noise of being a parent and working full-time, I love getting some time to do something really quiet, mindful, and perhaps even a bit boring.

GG: Starting with Mega Mosaic, you've established this unique niche of combining Minesweeper and Picross mechanics at a massive scale. What attracted you to this sort of logic-based puzzle game? What was your design and iteration process to arrive at your final mosaic puzzle mechanics?

MF: I can't claim any ownership of the puzzle mechanics I use; I'd been playing around for some time with the Mosaic puzzle in Simon Tatham's excellent portable puzzle collection. I'd set the puzzle to its maximum size (50x50) and had it running in the background for days at a time, picking it up in the gaps between meetings and making small chunks of progress. I loved it, but I wasn't satisfied. I wanted it to be MUCH bigger. I wanted to chip away at a single puzzle for weeks. I had the idea that while filling it in, you could be revealing a giant pixel art collage. Reddit's r/place was the inspiration for this. I wanted a completely random collage of strange pixel art. I created the borders for the grid and handed it over to two different pixel artists, asking them to fill the board with any random stuff they liked, then picked my favourites from both and combined them.

The game was simple to build and instantly fun and addictive. In fact, I had to set firm rules for myself to not play the game when I was supposed to be developing it, as giving a new feature a quick playtest for 2 minutes could easily turn into me accidentally playing the game for an hour or more. I had no idea if anyone else would have any interest in solving such a huge puzzle or if it was just a weird, boring thing that only appealed to me, so I finished it as quickly as possible and pushed it straight onto Steam with almost no fanfare, then responded as quickly as I could to player feedback and suggestions.

With Mega Mosaic, the fact that the borders between regions were 1 tile thick made the code a lot more complex than it needed to be (it has to do things like keep showing clue numbers in solved regions in case they're still useful for a neighbouring area). It also meant that some players felt cheated because all these big lines of tiles on the board had already been solved for them. So, for Proverbs, I decided to ditch the thick borders. But there was a new problem... without the pre-filled tiles crossing the board, there were far fewer starting points when working on the puzzle, and they were all 0s, 9s, or 6s and 4s at the edges. It became obvious that each region needed to be a self-enclosed puzzle. The bonus was that the irregular shapes of regions now meant that any number from 0 to 9 could be a starting point.

I'd liked how in Mega Mosaic, the puzzle would occasionally frustrate you by allowing you to complete 90% of a region before you realised you'd have to start working on a completely different area and work your way round to complete it. This was lost when I switched to self-enclosed regions, but I think overall it was for the best.

GG: In Picross, the positive and negative spaces of the puzzle form a basic visual of the image that will ultimately be rendered in more detail after you find the solution. Was this something you tried but eliminated during your design process? How do you think about the relationship between the puzzle-solving process and the final revealed image?

MF: This is a very common complaint, but in all honesty, I've not yet attempted to tackle it. It could be a lack of imagination on my part, but I struggle to imagine how some of the illustrations I use would convert into black-and-white pixel art, and whether the result would be fun to solve. Particularly if you have a large flat block of colour, how does that translate? Do I have a big region of empty or filled tiles for players to paint? Do I use repetitive dithering patterns to fill it?

It's still something that I may revisit, but at the moment it feels like a significant amount of work which could potentially just make the game worse, which is why it's always been prioritised below other improvements.

GG: I assume you’re using an algorithm to design puzzles that are guaranteed to be solvable by logic. How have your tools evolved since your first mosaic puzzle game?

MF: Yes, that's right. I start by marking up every separate region in an illustration, and a starting solution that's random noise. The puzzle starts off with a number clue visible on every tile. I have a solver that can make simple (and now advanced) deductions, and I use that to check that every region is solvable in this state. Not every solution is solvable, even with every number visible, so for any region that is only partly solved, I randomise the tiles that aren't solvable and try again. The algorithm to prune the full clue set is simple. It just visits every clue number in a region in a random order and tries removing it. If the region is still solvable without that number, then the number is discarded forever. By brute forcing this process on every tile in the puzzle, you end up with a set of clues where the puzzle is guaranteed to be solvable and where there are no redundant clues.

The tools have come a long way since the first game, but they're still quite fiddly to use. Hopefully, one day I will have a set of tools that anyone could use to create their own puzzles.

GG: In terms of puzzle and game design, how do you balance creating something that's both a relaxing background activity and mentally engaging? How did you arrive at the specific delineations of difficulty levels in Mosaic of the Strange, when earlier games like Proverbs and Mega Mosaic didn’t feature those options (please correct me if I’m wrong about that)?

MF: The simplicity of the mosaic games had been a common bit of feedback. I think if you've played something like Tametsi or Bombe, the puzzle can feel insultingly trivial, and some players would see it as a waste of time. But I think realistically, it can't be relaxing and a really challenging puzzle at the same time. Playing Mosaic of the Strange is a completely different game depending on whether you're playing on Classic or Special Agent difficulty, and those harder difficulties are not the same meditative experience that the series is known for. But it's quite hard to communicate that you're getting such a different experience with a set of difficulty options.

I can tell the puzzle generator that I want it to create a set of clues where the player has to make a certain ratio of simple deductions vs advanced deductions to solve it. I tuned these myself by playing various percentages and seeing what felt right. It's something like 2% advanced deductions on rookie, going up to 6% on Field Agent. But Special Agent is different. On Special Agent, I removed the cap completely and let the algorithm do its worst. It ends up being more like 40% advanced deductions, and it is extremely tough. I decided to put this out as a test in the demo, and originally felt like it was too over-the-top for the final release. But when one player left a glowing review after spending over 24 hours solving the demo on Special Agent, I decided to leave it as is.

GG: What drives your choice of themes for your games? I’m especially curious about what led you to pick the Bruegel the Elder painting “Netherlandish Proverbs” for Proverbs.

MF: Netherlandish Proverbs is a fascinating painting. There was a print of it that hung in my secondary school, just outside of the room where I had piano lessons. While waiting for lessons, my friends and I would pore over the image, trying to identify all the proverbs Bruegel had hidden throughout. I wanted to follow up Mega Mosaic with a single, really busy scene, and this painting was perfect. It's basically a Renaissance Where's Waldo? I also loved the idea of putting something as ludicrously specific on Steam as a game all about a single (moderately obscure) painting.

My later games have more text content, so I tend to opt for Wikipedia rabbit holes that fascinate me personally. The idea for Mosaic Retrospective came from the *202X According to Blower* series of jigsaw puzzles published each year by the Telegraph in the UK. I'm not a particularly political person, but the idea of creating a time capsule of real-world news stories really fascinated me. I also think that the game covers stuff that most game developers would steer well away from. Games are generally considered too commercial and too juvenile to talk about the real world, and I guess I felt strangely compelled to try breaking that taboo.

The fact that a simple mosaic puzzle game is quick and inexpensive to make opened up exciting possibilities; it meant I could create and release an entire game for free as a charity fundraising exercise, without any danger of Divide the Plunder running out of money.

GG: I’m fascinated by the evolution from your earlier massive canvas mural puzzle games into a narrative format in For Mosaic of the Strange. What were your inspirations, aside from the obvious The X-Files? Are paranormal events a particular area of interest for you? How did you go about picking the stories you highlight with each puzzle?

MF: Mosaic of the Strange was inspired by a couple of things I was obsessed with in the 90s... Weird: Truth is Stranger than Fiction, a now completely forgotten myst-like CD-ROM adventure that was also a multimedia encyclopedia of paranormal stuff, and of course, The X-Files. I became much more of a skeptic as I got older, but I still love that thrill of reading about weird, mysterious stuff and suspending my disbelief. One of the reasons that Mosaic of the Strange was delayed was that the paranormal case files were a real passion project, and I spent months selecting, researching, and writing them.

GG: What's a question you wish I had asked, and what's the answer?

MF: “What’s next?”

I have some ideas for mosaic-style games in the future, but I'm also going to be prototyping some very exciting new concepts in the near future. Make sure to follow Divide the Plunder on Steam or social media to hear more when the time comes!