This is a submission for the June Solstice Game Jam.
Bletchley's Longest Day is a browser-based cipher escape game set inside a fictional Bletchley Park night shift.
The player has to stop a U-boat convoy attack before dawn by clearing five rooms. Each room contains three escalating locks, so the full escape requires 15 solved puzzles. The game combines Caesar shifts, A1Z26 number decoding, Morse, anagrams, fragment ordering, a visible countdown timer, mistake penalties, hint penalties, account-based score saving, and a best-score leaderboard.
The solstice theme became the core dramatic clock: night is running out, first light is coming, and the player has to decode the final signal before dawn.
The demo shows the opening briefing, the three-lock room flow, the Gemini hint penalty, and the final victory state that only appears after all 15 locks are cleared.
Live game: [https://bletchleys-longest-day.onrender.com](https://bletchleys-longest-day.onrender.com)
Repository: [https://github.com/himanshu748/bletchleys-longest-day](https://github.com/himanshu748/bletchleys-longest-day)
The game is a lightweight Node-served browser app. The front end is a hand-built HTML/CSS/JavaScript game surface, while server.js
serves static files and protects the Gemini API key behind a server-side /api/hint
endpoint.
The main design goal was to make the game feel like a tense intelligence desk rather than a generic puzzle page. Every room has atmosphere, evidence props, lock-specific copy, feedback states, and a timer that is always part of the pressure.
The puzzle structure was tuned around three ideas:
Google Gemini is used as a server-side hint officer. When a signed-in player asks for help, the game sends Gemini the active lock name, prompt, mechanism, visible puzzle text, failed attempts and hint level. Gemini then returns a short, question-specific nudge without revealing answer words. There is also an answer guard and fallback hint system so the game never depends blindly on model output.
Antigravity helped drive the build loop: implementing, checking, playtesting, tightening responsive UI and iterating on the final submission assets.
For hosting, the game runs on Render. Supabase handles authentication and leaderboard storage so each username has one best score rather than repeated leaderboard spam. I am submitting for Best Google AI Usage because Gemini is not just decorative here. It is part of the gameplay economy: hints are question-specific, limited, penalized and unavailable to guests.
Antigravity helped drive the build loop: implementing, checking, playtesting, tightening responsive UI, and iterating on the final submission assets. Also veo is used through higgsfield for assets.
I am also submitting for Best Ode to Alan Turing. The game is built around codebreaking under time pressure, Bletchley Park atmosphere, wartime signals, and the feeling of solving small pieces of a larger intelligence picture before the world changes at dawn.
I like that the game does not treat AI as a free answer button. Gemini is useful, but it costs time and score. The best run still belongs to the player who thinks clearly under pressure.
The final shape feels like a compact escape room: readable enough to play on desktop or mobile, but hard enough that a clean 15/15 run feels earned.