Good Sudoku

Sudoku has a software problem, not a design problem. The puzzle itself is close to perfect — nine rows, nine columns, nine boxes, one rule — and it has survived four decades of newspapers, airline seatbacks and knockoff apps stuffed with interstitial ads for mobile RPGs. What it has never had is a good digital home. Open the App Store, search “sudoku,” and you get a wall of near-identical grids wrapped in banner ads, gem economies and hint buttons that do nothing but hand you the answer and charge you for the privilege.

Good Sudoku is the response to that mess, and its thesis is right there in the name. It comes from Zach Gage and Jack Schlesinger working under the STFJ banner — the same design partnership behind Really Bad Chess, Card of Darkness and Knotwords, a studio with a consistent pattern of taking a calcified classic and asking what it would look like if someone had actually designed the interface. That pedigree matters here, because Good Sudoku is not attempting to reinvent sudoku. It is attempting to reinvent everything you touch on the way to solving one.

The scope is serious. A large library of hand-checked puzzles across five difficulty tiers, each tier transparently labeled with the solving techniques it demands. Three modes — Good, Arcade and Eternal — that split the audience between contemplative solvers and score-chasers. Daily puzzles with global leaderboards. A practice mode that drills individual techniques in isolation. A custom-puzzle importer that lets you type in the board from your Sunday paper, or a variant like Miracle Sudoku, and share it. It launched on iOS in July 2020 as a free download, and currently holds a 4.3 out of 5 from 1,316 App Store ratings.

The market position is unusual: this is a premium-feeling product with a free entry point, competing against free-with-ad clutter by being conspicuously, aggressively better designed.

• The Hint System: The headline act. Rather than filling in a cell, the hint engine reads the current board state and your demonstrated skill level, then walks you through the technique that unlocks the next move — step by step, with visual annotation. It is a tutor, not a cheat button.
• Technique-Labeled Difficulty: Every tier tells you what it will require. You know before you start whether a board wants a Hidden Pair or a Swordfish, so difficulty stops being a vague vibe and becomes a curriculum.
• Drudgery Automation: Automatic candidate notes, smart highlighting, cascading eliminations and unlimited undo. The bookkeeping that makes hard sudoku tedious on paper is simply handled.
• Three Modes + Dailies: Good for slow, deliberate solving; Arcade for fast scoring; Eternal for the endless variety; daily puzzles with global leaderboards for the competitive itch.
• Practice Mode & Custom Import: Isolated drills for a single technique, plus an importer that ingests newspaper boards and variants like Miracle Sudoku.

The Gameplay Loop

The core insight of Good Sudoku is that most of what you do in a sudoku app isn’t solving. It’s clerical work. Penciling candidates into eighty-one cells, erasing them one at a time as constraints tighten, squinting to see whether that 7 in row four is still viable. That’s not puzzle-solving. That’s data entry with a stylus.

Gage and Schlesinger strip it out. Turn on auto-notes and the grid populates every candidate for you; place a digit and the eliminations cascade across the row, column and box. What remains is the part that requires a brain — pattern recognition. The design aims for a dramatically higher density of interesting decisions per minute: a hard puzzle that would take most of its time on newsprint maintaining state becomes a compact sequence of genuine deductions.

Purists hate this. There’s a persistent minority in the App Store reviews arguing that the automation makes puzzles too easy, and they aren’t wrong so much as they’re measuring the wrong thing. Yes, the app removes difficulty — but it removes the difficulty of clerical accuracy, not the difficulty of logic. If your pleasure comes from the meditative rhythm of hand-marking a grid, the tools are optional and can be left off. That’s the correct answer to the complaint, and Good Sudoku already implements it.

The Hint System Is the Product

Everything else is polish. This is the reason to install the app.

Standard sudoku hints are a moral failure. You get stuck, you tap the lightbulb, a number appears, and you have learned nothing except that you were stuck. It short-circuits the entire point of the exercise while draining a currency the app wants to sell you.

Good Sudoku’s hint engine does the opposite. It evaluates the board, identifies the technique that actually resolves the current position, checks what you’ve already demonstrated you understand, and then teaches — highlighting the relevant cells, naming the pattern, explaining why the elimination is valid. When you hit the wall on an expert board, it doesn’t rescue you. It shows you the shape of the thing you couldn’t see.

The consequence is a genuine skill ramp. The design is built to carry solvers from barely comfortable with Naked Pairs toward executing X-Wings, Swordfish, Jellyfish and XYZ-Wings — techniques that, on paper, live in obscure forum posts and PDF tutorials nobody finishes. Combine that with the practice mode’s isolated drills and the technique-labeled difficulty tiers, and Good Sudoku becomes something rare in the puzzle category: software with a pedagogy. Most puzzle apps sell you content. This one builds capability, and the content is the delivery mechanism.

Modes and Structure

The three-mode split is smarter than it first appears. Good is the flagship: full toolset, no clock pressure, the mode where the teaching happens. Arcade inverts it — fast, scored, adrenal, closer to a twitch game than a logic puzzle. Eternal keeps the tap flowing indefinitely. Daily puzzles with leaderboards bolt on a light social layer without demanding an account-based friend graph.

The custom importer is the deep-cut feature and the one that signals real affection for the hobby. Typing in a newspaper grid to solve it with proper tools is a quality-of-life win. Importing a Miracle Sudoku — a variant that went viral on Cracking the Cryptic — and sharing it with a friend is fan service, and it lands.

Friction Points

Onboarding is dense. Between five tiers, three modes, practice drills, the importer and a toolbar of automation toggles, the first session presents a lot of surface. The app handles it reasonably, but a returning-after-two-months user will need a minute to reorient.

And the paywall is the real irritant — not that it exists, but where it sits. Dark mode sits behind a paid unlock. Charging for a full puzzle library and extra modes is entirely defensible. Charging for the ability to not have a white rectangle fired into your retinas at 11pm is the kind of decision that generates one-star reviews from people who would have happily paid, and it’s a recurring complaint in the ratings for good reason.

The aesthetic is flat, bright and confident — big legible numerals, generous tap targets, saturated accent colors doing real informational work rather than decoration. There’s no wood-grain skeuomorphism, no fake newsprint, no leather. It looks like software made in this decade by people who have opinions about typography.

Highlighting is the standout craft detail. Select a digit and every related cell, candidate and conflict lights up in a visual hierarchy you can parse without conscious effort. That sounds trivial. It is the difference between scanning a grid and reading one.

Performance-wise, there’s little reason for concern on design grounds alone: a 2D puzzle of this scope is light on hardware, and the animation work is built to communicate causality without slowing you down.

This is an iOS-native design, not a port, and the touch model shows it. The number pad sits within thumb reach, the cell targets are sized for fingers rather than cursors, and toggling between entry and note modes is a single deliberate tap instead of a modifier key. Sudoku is one of the few genres where touch is genuinely superior to mouse and keyboard — direct manipulation of a spatial grid is what fingers are for — and Good Sudoku exploits that fully.

Session length maps well to phone reality. Arcade fits a subway platform; a Good-mode expert board fits a lunch break. On iPad the extra canvas makes candidate scanning easier, and the layout is built to scale without stranding controls in awkward corners.

Good Sudoku is what happens when actual designers look at a genre that stopped trying years ago. The puzzles aren’t new — they can’t be, that’s the nature of sudoku — but the software around them is a meaningful step forward for the category. The hint system alone justifies the download: it treats getting stuck as a teaching opportunity rather than a monetization event, and it’s built to make you better at the game.

The paid unlock is reasonable for what’s behind it and a self-inflicted wound for how it’s structured. Put dark mode in the free tier, and the most common complaint about this app largely evaporates.

We rate it a solid recommendation for anyone who wants to actually improve at sudoku — with the caveat that the free tier is more gateway than product, and purists should know what they’re getting into.