Solstice cipher: AI-built codebreaking game launches

Solstice Cipher, a single-file browser game, lets players decode Caesar, substitution, and Vigenère ciphers while racing against a daylight timer [Dev.to]. The game is built with vanilla JavaScript, CSS, and the Web Audio API, loading instantly on modern browsers [GitHub].

Each of the three core levels introduces a real cryptographic technique: Level 1 uses a Caesar shift, Level 2 a mono-alphabetic substitution, and Level 3 a Vigenère cipher. An in-game "Decrypt-O-Matic" helper adapts its UI per level, teaching players the math behind each cipher [Dev.to].

After completing the ciphers, the game swaps to a four-passage Turing Test, where two passages are human-written and two are generated by a language model. The player must label each, with no win/lose condition, encouraging reflection [GitHub].

The project was generated from a single prompt to Google Antigravity, an AI code-generation tool, then manually verified. The author discovered a one-character bug in Level 2's ciphertext, highlighting the need for human QA even when AI writes the logic [GitHub].

Solstice Cipher demonstrates that AI can produce complete interactive experiences, such as playable games, without traditional development teams [Dev.to]. The browser-only delivery removes friction for learning cryptography, as educators can embed the game in curricula without worrying about installations or platform dependencies [GitHub]. The built-in Turing Test forces players to confront AI-generated text, making the abstract "Imitation Game" concrete and highlighting the importance of critical evaluation [Dev.to].