The first time I opened Pell Puzzles I thought somebody had left a half-finished game of noughts and crosses on my screen. Eight X's, seven O's, a 6x6 grid and the numbers 1 to 8 down the side. Nobody plays noughts and crosses on a 6x6 board, so clearly something else was going on.

TLDR: Looks a bit like noughts and crosses, feels a bit like a labyrinth but plays like a proper logic puzzle. Perfect for anyone who grew up on pencil puzzles, and anybody who wants a couple of quiet, ad-free minutes of thinking with their morning coffee.

Pell Puzzles is made by Brandan, who writes the achromath Substack and calls himself a "serially obsessive analytic creative and general purpose games dork"^[1]. In January 2024 he wrote about Pell Tiles: wrap strips of squares around each other in a spiral, each strip one square longer than the last, and every now and then they fill a perfect rectangle.^[2] Strips of length 1 to 8 add up to 36, which happens to be a 6x6 square. A year later he asked the obvious next question, "Can we turn this spiral into a puzzle?",^[3] hid the strips and left only their ends on the board as X's and O's. The daily version has been running since December 2025,^[5] let's take a look how it stands against my DLE review framework. The article contains screenshots with spoilers of the 26 October 2026 puzzle.

How to play

1. On the menu, tap Daily Puzzle. The board opens and the timer starts straight away.
2. Read the grid: a 6x6 board of X's, O's and empty cells. You have to draw exactly 8 paths, one of each length from 1 to 8. They add up to 36, so every cell ends up in a path.
3. For lengths 2 to 8, drag from an X to an O (or the other way round) through empty cells, moving up, down, left or right. The path stops by itself when it reaches the other clue.
4. For the length 1 path, just tap a lone X.
5. A path can't touch itself side by side (corners are fine), and it can't fill a 2x2 block. If you try, the cell gives a little shake and the path won't go there.
6. To fix a mistake, tap a path to cut it at that cell, drag an end backwards to shorten it, drag one loose end into another to join them, or hit Clear to wipe the board.
7. Keep an eye on the 1 to 8 tracker next to the board (under it on a phone): a length you've used goes dim, and a length you've drawn twice lights up white.
8. Fill the board with all eight lengths and a "Solved!" card pops up with your time and the order you found the paths in.

Concept 10/10

This is a new puzzle, which is rarer than you'd think. It kinda looks similar to the connect-the-dots games at the back of a logic magazine, but the twist is all its own: every path has to be a different length. That one rule turns the numbers 1 to 8 into your sharpest tool. Once you've drawn the 3, no other pair on the board can be joined by three cells, and you lean on that all the way through.

I love the main menu, that's completely atypical, text written in all kinds of directions but after a closer look, you realize it is a solved Pell board, every button is one of the strips, and the little empty square in the middle is standing in for the 1. I love that kind of detail.

Time to first guess 10/10

The good news first. There's no account wall, no welcome popup, and the game doesn't even throw a cookie pop-up at you, great! You land on the menu, tap Daily Puzzle, and the board is right there with the clock already running.

The rules are well made too. The How to Play walkthrough covers the whole game in four short screens, 85 words if you count the headings, which is about what Wordle needs for its whole rules box, and three of those screens have a little looping video showing exactly what a move looks like. A fifth screen covers the controls.

Gameplay 26/30

This is where Pell earns its keep. My whole solve was deduction, not a single guess, and the length rule did the heavy lifting the entire way.

(I'm counting rows and columns from the top left, so R1C1 is the top-left corner.)

Today's board had three empty corners, and an empty corner is a gift: the only way to fill it is with a path running through it between its two neighbours. Brandan's own write-up says easy puzzles have "gimmes, especially in the corners",^[4] and he's right. The bottom-right corner handed me the 4 on move 1, from X(R4C6) down and round into O(R6C5).

Move 2 was the bottom-left corner, and it had a nice little catch. X(R5C1) has to go round the corner and along the bottom row, and I first eyed stopping at O(R5C3) for a 5. But that would have left R6C4 with only one free neighbour, and an empty cell needs two, one for the path to come in and one to go out. So the path runs one cell further and climbs into O(R5C4), a 6.

Then it went quickly. X(R5C5) was now boxed in with nowhere to go, so it's the 1, one tap (move 3). O(R5C3) could only go straight up into X(R4C3), so that's the 2 (move 4). And O(R5C2), squeezed on three sides, had to climb, which left O(R4C1) a single way out and gave me the 3 up the left wall (move 5).

Move 6 is the one I enjoyed most. The path out of O(R5C2) was heading up the second column, and at R3C2 it could either carry on up or turn right. The answer came from a corner I hadn't touched yet. Up in the top left, O(R1C1) could have reached X(R1C3) in three cells, but the 3 was already spent, so it had to drop down into R2C2 instead. That took R2C2 away, pushed the long path right, and the empty R4C4, which only had two free neighbours left, finished it off into X(R4C5). A 7, decided by a length I'd used up one move earlier. That's the whole trick of this game, and it feels great every time it clicks.

Moves 7 and 8: the top-right corner gave me the 5 along the top row, and the last six empty cells made the 8.

It's completely fair, with one solution and every step something you can reason out, and it's 100% skill, 0% luck. The game also quietly refuses illegal moves. Try to make a path touch itself and the cell shakes and won't take it, so you never lose a minute to a rule you forgot.

Juice 5/10

The basics are there. A path snaps from cell to cell as you drag, a used length dims on the tracker, and if you draw the same length twice that number lights up white and grows a little so you can't miss it. Illegal moves get the little shake.

It's minimalistic. There's no sound, the paths stay the same flat grey from your first move to your last, and nothing builds up to the finish. The moment your eighth path lands, the board is swapped for a plain "Solved!" card, so the thing you just built disappears and you have to tap "View Solved Puzzle" to look at it.

I could imagine a little animation that would reproduce your solution would bring a bit more energy into the purist black and white look. Or even just a pulsing board when solved, combined with the results just underneath the board would increase the juice levels significantly.

Visuals 8/10

Black, white, grey, one monospace font and chunky white borders. It's a strict look and it's applied everywhere, from the menu through the rules to the archive. Nothing fights the board for attention, and there isn't a single ad anywhere.

The menu-as-puzzle is the best-looking screen, and a finished board has a nice graphic quality to it. A couple of things cost points. The small print (the puzzle code, "Hide Timer", "Report an issue") is dark grey on near-black and hard to read. And on my laptop the archive table is wider than its box, so the Solve % column hides off to the right behind a sideways scroll, even though there's plenty space on the screen.

Mobile experience 9/10

The puzzle screen is excellent on a phone. The board fills the width with cells about 56 pixels across, plenty for a thumb, dragging a path doesn't drag the page around with it, and the 1 to 8 tracker moves under the board as a row of chips. The whole thing fits on one screen without scrolling, and with no ads there's nothing to cover it.

Compared to desktop I'd call the phone the better way to play, because drawing a path with your finger is the natural motion for this game. The rules reflow nicely and the win card fits without any scrolling.

Two misses. Share Result only copies the text and doesn't open the phone's share sheet, so it's copy, switch apps, paste. And the archive and leaderboard tables are far wider than the screen. The archive is more than twice the width of my phone, so you see the date and your own time, and everything else (fastest, median, solve rate) means swiping sideways inside the table.

Share grid 7/10

Share Result copies this:

Pell Puzzle 2026-10-26
Time: 02:32
4️⃣ 6️⃣ 1️⃣ 2️⃣ 3️⃣ 7️⃣ 5️⃣ 8️⃣

Play at: https://pell.achromath.com/

It's spoiler-free (knowing I found the 4 first tells you nothing about where it goes), and it really is the path to victory in abstract form: the order I cracked the board in. Anybody else who did today's puzzle can look at "4 6 1 2" and know I started in the bottom corners and let them cascade, which is a nice little "oh, you went that way" moment between friends. The time is the brag.

What it doesn't have is a picture. A row of keycap emojis doesn't read at a glance the way a colour grid does, and a clean solve looks exactly the same as one where you drew, cut and redrew half the board. So maybe a heat map style 6x6 grid made out of emoji 🟩 where the path landed on first attempt and 🟨 or 🟥 on spots where mistakes were made could be a nice touch.

Streak and stats 3/3

The Stats panel counts your solves, shows your best and average time and draws a little histogram of solve times, and there's a Share Stats button too. It remembers you without making you sign up, and logging in is only there if you want your progress on more than one device.

There's no streak and yet, there's quite a few people on the leaderboards who solved all the 328 available games. Well done.

Leaderboard 2/2

There's a proper global leaderboard, and it's smarter than most. Instead of crowning whoever was quickest this morning, it ranks players by how many puzzles they've solved "fast", meaning under the global median (1:28 right now), with extra columns for solves under 10 seconds, 30 seconds, one minute and two minutes. Counting fast solves over hundreds of days is also much harder to game than a daily top ten, and on top of that the archive names the fastest solver for every single day.

Only players who've set a display name show up, which makes sense, but would be nice to see yourself on the leaderboards even just as an anonymous guest, not visible to others, obviously.

Archive 5/5

Full marks. Every puzzle back to 3 December 2025 is there and playable with one tap,^[5] and each row shows your time, the fastest time and who set it, the median, how many people solved it and the solve rate, plus a time for "Pellbot", which I'm guessing is Brandan's own solver. The columns sort, so hunting down the nastiest days by median takes two clicks.

That's a properly bingeable back catalogue, and the per-day stats make it more fun than a plain list of dates.

Monetization +1

There's nothing to buy here. No ads, no paid hints, and the game itself doesn't even have a support button.

That's almost the purist territory, but the achromath tile on the menu takes you to Brandan's homepage, which has a Buy Me a Coffee link further down,^[1] so only +1 point here. Brandan, if you're reading this: put that coffee link on the win card. The people who've solved 327 of these would happily buy you one.

Verdict 86/102

Pell Puzzles is a proper logic puzzle with a rule you can explain in one breath, and that rule ends up guiding most of the solving for you. The archive and leaderboard are better than what plenty of bigger games ship, it plays great on a phone, and there isn't an ad in sight. It drops a few points for missing the opportunity to add some juice upon winning to make the players feel something more at the end, because the current win barely registers.

Who's it for? Sudoku people, anyone who grew up on pencil puzzles, and anybody who wants a couple of quiet, ad-free minutes of thinking with their morning coffee.

The DLE world is full of games that started with "what if Wordle, but…". This one started with somebody who couldn't stop thinking about a spiral of squares, and a bunch of regular players now turn up every single morning to draw on it. That's the kind of thing that makes me want to keep doing this.

That's my take. Played it too? Beat my 2:32? Not hard, I know. Review below, or check out more Pell Puzzles details on its page.

Have you not played Pell Puzzles yet? Go and give it a try right now.

-Peter

Sources

1. achromath, homepage and About page, Brandan's bio and the Buy Me a Coffee link
2. Pell Tiles, achromath on Substack (30 January 2024), the spiral of strips the game grew out of
3. Pell Puzzles, achromath on Substack (9 January 2025), turning the spiral into a puzzle
4. Cracking Pell Puzzles, achromath on Substack (4 January 2026), Brandan's own solving guide
5. Pell Puzzles archive, first puzzle dated 3 December 2025, every daily puzzle with its per-day stats