About this project
Just. Sudoku.
A sudoku app for iPhone and iPad with no ads, no pop-ups, and no timers. A new puzzle every day, 1,500 more in the campaign, big readable numbers, and hints that explain themselves. Pay once, play offline forever.
iPhone and iPad · iOS 15 or later · $0.99, no in-app purchases
Screenshots
The board fills the screen and the numbers stay large, even with tired eyes. Everything below is captured straight from the app.
Why it exists
Kitdoku started as a gift. One person in our life wanted a sudoku app they could open at the end of a long day without a fight. Every app they tried had ads between puzzles, pop-ups asking for money, and a timer ticking in the corner. They just wanted to play.
So we built one with the opposite priorities: a single one-time price, no account, no tracking, and no internet needed. Every helper is optional and has its own switch, so the app can be as gentle or as strict as the player likes. It shipped to the App Store in September 2026.
How it was built
Kitdoku is the same approach we use for client apps: a fast, lightweight web codebase that runs inside a native shell, with the logic kept separate from the interface so it can be tested hard and reused on other platforms later.
01
The app is a Svelte 5 and TypeScript web app bundled by Vite, wrapped in a native iOS shell by Capacitor. Only three Capacitor plugins are used: Preferences for storage, Haptics, and Status Bar. Everything else is plain browser APIs. No React, no UI kit, no web fonts, so the whole app stays under 50 MB with all 1,500 puzzles inside.
02
The solver, puzzle generator, technique library, and game controller are framework-free TypeScript with no Svelte imports. That keeps them trivially unit-testable. A single Svelte 5 runes module wraps the controller, persists state on every change, and exposes actions to the components. Components never touch game logic directly.
03
A technique-aware solver walks the board the way a person would: naked and hidden singles, locked candidates, naked and hidden pairs, and X-Wing. When a player taps Hint, the app finds the next logical step, names it, and explains in plain words why the digit goes there. The same trace grades every puzzle, so "Hard" means it actually needs harder techniques.
04
The generator builds a complete board with randomised backtracking, then digs holes while checking that exactly one solution remains and that the puzzle lands in the target difficulty tier. A script produced the 1,500 campaign puzzles ahead of time. The daily puzzle is seeded from the date and generated on the device, so every player gets the same puzzle without the app ever contacting a server.
05
There are no runtime network calls at all. Progress lives in versioned storage keys so a schema change can migrate one bucket without touching the others. On iOS every write is also mirrored to the iCloud key-value store through a small custom native plugin, so a player who deletes and reinstalls the app, or gets a new phone, keeps their streak.
06
Every sound is synthesised at runtime with the Web Audio API. Each digit plays its own note along a pentatonic scale, a wrong placement thuds, and solving a puzzle plays a short arpeggio. The sound design is expressed as data, so it is unit-tested like everything else. Haptics follow the same event plan.
07
The whole screen is a single CSS Grid with named areas. Portrait stacks header, board, toolbar, and number pad; landscape on iPad puts the board on the left and the controls on the right. The switch is one media query on aspect ratio, with no JavaScript branching and no separate tablet layout to keep in sync.
08
Vitest covers the core engine. Playwright drives the UI in WebKit at phone and tablet sizes to mirror the iOS web view, including adversarial input and corrupted-storage cases. A store-readiness suite enforces 44pt touch targets, accessible names, a clean console, and zero external requests. A smoke script builds, installs, and screenshots the app on the iOS simulator, and the App Store screenshots themselves are generated by Playwright from seeded game state.
Available now for iPhone and iPad. One purchase, no subscriptions, and nothing to sign up for.
We build iOS and Android apps for businesses, and as a white-label partner for agencies. Same care, same testing, your brand on the front.
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