四十秒の交差点
Free · play online in your browser, no download
You confess, she says no, and you wake up to the same Monday morning. A time-loop romance novel with nine endings in the browser, its code written almost entirely by Claude Code.
Official site vannangames.com, verified Nov 3, 2026. Play address linked from the game's page on VANNAN GAMES (vannangames.com), the developer's own site, which the developer's Zenn article links.
Where to play
Every platform this game is on. Links are checked against official sources; we never host or mirror games.
- Play free — official siteBrowserReleasedFree
Runs in a desktop or mobile browser. No download.
Browser (no download) · Mobile · Official link verified Nov 3, 2026.
About 四十秒の交差点
四十秒の交差点 is a free branching romance adventure (a visual novel) for the browser, in Japanese. On Monday 20 May, at a crossing at the foot of a hill whose green light lasts only forty seconds, the narrator meets Asuka Mochizuki, the classmate the narrator has liked for a year. The narrator confesses after school and is turned down; that night comes a dream of screeching brakes and a watch stopped at 8:05, and the next morning is 20 May again. Each loop splits the day into morning, lunch, after school and night, with sixteen places to choose from, so no single loop covers everything. Clues found carry over between loops, but pushing Asuka too hard fills a wariness gauge, and when it is full she closes up and the day ends in one of the endings. You name the protagonist and choose how the characters address you, which matters to the story. There are nine endings including a hidden one; reaching the true ending unlocks an epilogue and two stories told from other characters' viewpoints. One loop takes about 80–110 minutes and seeing every ending six to seven hours, with autosave in the browser and nine music tracks. It is the main story of VANNAN GAMES, a one-person site by kawaiy, a web engineer, most of whose other games share the same town. Per the developer, the code is almost all written by Claude Code, and Claude also drafted documents and scenario text and did reviews, while the illustrations were generated with ChatGPT and the music with Suno; the site credits the scenario and development to kawaiy. Plain HTML, CSS and JavaScript with no framework. Free in desktop and phone browsers.
How it was built
VerifiedIn a Zenn article (23 Aug 2026) about building the eight-game site in 34 days, the developer lists the division of work as “Claude : コード、ドキュメント、シナリオの下書き、レビュー” (Claude: code, documents, scenario drafts, reviews) and writes “コードはほぼClaude Codeに書かせています。” (I have Claude Code write almost all of the code.) In August 2026 the median change was 1,476 lines a day, up to 7,686. Because mistakes grew as fast as the code, seven check scripts (page format, broken links, stale generated files, save-data export keys) and four generator scripts (sitemap, structured data, RSS, game list) run from a Claude Code Stop hook every time the agent finishes a reply, and again on GitHub Actions. The developer kept for themselves whether a game is fun, the consistency of the shared world (what each story reveals) and decisions about what not to do.
Generated the illustrations from request files kept in the repository, one code block per image (27 of 32 request files were for images), with fixed rules such as a transparent background without a checkerboard; keeping one character consistent across ten portraits took the most time, per the developer.
Plain HTML, CSS and JavaScript with no framework, bundler or transpiler; Python scripts generate the sitemap and structured data, and whatever is merged to main is served by Tencent Cloud EdgeOne Pages. No servers: game state lives in the browser's localStorage, with a page to export and restore all saves. Claude Code writes almost all of the code under automatic checks run by a Stop hook; ChatGPT generates the illustrations and Suno the music (regenerated on a paid plan after the developer found the free-plan terms did not fit); sound effects are generated as waveforms with Python. The whole site (eight games) took 34 days from the first commit on 20 Jul 2026, about 90 hours, with 751 commits and 17,218 lines of JavaScript by 23 Aug 2026.
- Engine / framework
- None (vanilla JavaScript)
- Languages
- JavaScript
- Team size
- 1 (solo)Developer ReportedVANNAN GAMES
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- Not disclosed
“コードはほぼClaude Codeに書かせています。”- Eight browser games in 34 days: Claude, ChatGPT and Suno, and what could not be handed off (Zenn, Japanese)
- Game page on VANNAN GAMES (Japanese)
Verification notes: AI use, the workflow and the site figures come from the developer's Zenn article (23 Aug 2026, 02:03 JST), re-read through Zenn's API on 7 Nov 2026; it links vannangames.com. The article covers the whole site and does not name individual games, so the Claude Code statement is applied to each of its games. Story, structure, endings, play time, release date (公開日 20 Jul 2026, last updated 21 Aug 2026) and credits (シナリオ・開発：kawaiy; illustrations generated with ChatGPT, BGM with Suno) come from the game's page; controls, autosave and the wariness gauge from the in-game guide and the how-to page, all read on 7 Nov 2026. Note the addresses: the novel plays at /games/yonjubyo/, while /games/yonjubyo40/ is the separate one-button action game よんじゅうびょう。. The site's operator page names kawaiy (個人) as the operator and says illustrations use ChatGPT and music Suno; the site's home page says everything from planning to music is made by one person, with the music made by AI. The article says Claude drafted scenario text; the site credits the scenario to kawaiy; both are recorded. The English title is our translation; there is no official English title. The game's scripts contain no AI service addresses; the site loads Google Analytics. The Japanese interface was observed on the page (lang="ja"); no other language option was found. The game was not played to the end.
Development history
Released on VANNAN GAMES, the day of the site's first commit and launch.
The developer's Zenn article describes building the eight-game site with Claude Code writing almost all of the code.
DeveloperZenn (kawaiy)
Game performance
Each figure measures something different — concurrent players, owners, downloads and sales are never interchangeable and are never added together. Labels show where each number comes from.
Browser (official site)
Free in modern desktop and phone browsers, with no install or account; progress autosaves in the browser and can be exported from the site's backup page. The site accepts optional support through OFUSE.
No public metrics recorded for this listing.
Not publicly available: Concurrent players (site), Monthly revenue, Gross revenue.
Sales & revenue (all platforms)
Browser game — there are no downloads to count.
Reviews & rankings
Not yet reviewed by our editors.
Not currently ranked.
Sources
| Source | Type | Published | Accessed |
|---|---|---|---|
| 34日でブラウザゲーム8本のサイトを立てた。Claude・ChatGPT・Sunoの分担と、丸投げできなかったもの Zenn (kawaiy) · Japanese | Devlog | Aug 23, 2026 | Nov 3, 2026 |
| 四十秒の交差点｜分岐型恋愛アドベンチャー｜VANNAN GAMES VANNAN GAMES · Japanese | Official site | Jul 20, 2026 | Nov 3, 2026 |
| VANNAN GAMESについて｜運営者情報 VANNAN GAMES · Japanese | Official site | Not confirmed | Nov 3, 2026 |
| VANNAN GAMES VANNAN GAMES · Japanese | Official site | Not confirmed | Nov 3, 2026 |
| Official game page (language check) VANNAN GAMES | Official site | Not confirmed | Nov 3, 2026 |
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