Game
Cypher
Bulls & Cows (Mastermind) in the browser: play solo, against an AI, with someone on the same phone, or online peer-to-peer with a QR code invite.

Cypher is Bulls & Cows, also known as Mastermind: you guess a code of digits, and after each try you learn how many digits are in the right place and how many are only in the code.
Game modes:
- solo, against a random code
- against an AI that works out its guesses in a Web Worker
- two players on the same device, taking turns
- online peer-to-peer through PeerJS, with the room invite shared as a QR code
The game keeps a history of matches with win rate and average number of tries, and can save a result as an image. It has difficulty levels, a Romanian and English interface, sound, haptics on phones, and light and dark themes. It installs as a PWA and runs fully offline after the first load.
Stack: React 19, TypeScript, Vite, Tailwind CSS v4, Zustand, PeerJS, Framer Motion, Workbox and Vitest.
Screenshots
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