珊瑚海海战 · Coral Sea
Free · play online in your browser, no download
A turn-based hex wargame of the Battle of the Coral Sea: as Rear Admiral Fletcher, find the Japanese carriers under cloud, time and range limits and strike first.
Official site flanker.github.io, verified Nov 3, 2026. GitHub Pages site of the flanker account that owns the source repository; the developer's Bilibili video points viewers to the playable versions.
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- Play free — official siteBrowserReleasedFree
Runs in a desktop browser. No download.
Browser (no download) · Official link verified Nov 3, 2026.
About 珊瑚海海战 · Coral Sea
A free, single-player, turn-based hex wargame of the naval and air battle in the Coral Sea in May 1942, in the browser. You play Rear Admiral Fletcher, commanding the Yorktown and Lexington task forces and Crace's cruiser group against the Japanese carriers Shōkaku, Zuikaku and Shōhō. One hex is 30 nautical miles and one turn is one hour, on a 30 × 20 map of the whole sea. Each turn you move task forces, put fighters up on combat air patrol, send SBD squadrons or cruiser floatplanes to search sectors, and plan strikes, with a timeline that warns when aircraft would land after sunset. The README stresses that about a third of scouting reports are wrong, that cloud hides fleets and spoils interceptions, that night halves flight operations, and that carriers have a limited number of deck actions per hour; American carriers get radar warning of incoming raids, bombs can start spreading fires, and victory is scored in points, with an immediate loss if the Japanese convoy reaches Port Moresby. There are three scenarios (a tutorial, the 8 May carrier duel and a 50-turn campaign for 6 to 8 May) and three difficulty levels. The developer, flanker (写代码的flanker on Bilibili), says two web wargames about the battle were produced overnight by letting AI agents loop on their own, one with Claude Code (Claude Fable 5.1) and one with Codex (GPT-6 Astra); this is the Claude Code version, and the Codex one is CONTACT. Ten of the repository's eleven commits carry a Claude Fable 5.1 co-author trailer. The interface is in Chinese, with ship and aircraft names in Chinese and English; the source is public on GitHub.
How it was built
Partially verifiedIn the description of a Bilibili video (7 Sep 2026) the developer writes that, with Codex GPT-6 Astra and Claude Code Fable 5.1 in the news, they let an agent “loop” on its own overnight and it produced two web wargames (“晚上让 Agent 自己 loop 出来了两个网页版的战棋游戏”), and that the generated source code and both games are public. This repository is the Claude version. Its design document (v0.1, 6 Sep 2026) plans the build in milestones, and the commits follow them: engine skeleton, hex map and projection, the Japanese AI, campaigns, polish and a full end-to-end test, all on 6 Sep 2026.
- Observed10 of the 11 commits in the repository (6 Sep 2026, 10:37 to 16:10 Beijing time, full clone on 8 Nov 2026) carry the trailer “Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>”. — GitHub (flanker)
A static front-end page with no back end, built with Vite: a pure TypeScript rules engine (hex geometry, a geographic projection, rule tables, a clock, scenarios, command validation and turn resolution in the order weather, movement, flight, detection, combat, recovery, damage control, time and victory) and a React + SVG interface with zustand state. Every random number comes from a seeded mulberry32 generator, so the same seed and commands give the same game. The Japanese side is played by conventional game AI (a heat map, a state machine and manoeuvre scoring), not a language model. The repository has Vitest unit tests, Playwright end-to-end tests and AI-versus-AI simulation scripts, and the README sets an acceptance target of a 35–65% American win rate over 100 simulated games of the 8 May scenario. The design document lists the historical timeline the scenarios and numbers are based on. No AI service is called by the game.
- Engine / framework
- React + SVG (TypeScript, Vite)
- Languages
- TypeScript
- Team size
- Not disclosed
- Initial build time
- Overnight (agent loop)Developer ReportedBilibili (写代码的flanker)
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- Not disclosed
“趁着 Codex GPT-6 Astra 和 Claude Code Fable 5.1 的火热，就晚上让 Agent 自己 loop 出来了两个网页版的战棋游戏。”- Source code (GitHub)
- Developer video: two web wargames made with GPT-6 and Fable 5.1 (Bilibili, Chinese)
Verification notes: AI use from the description of the developer's Bilibili video (BV1Ljbw63EQ4, uploaded 7 Sep 2026, 11:15 UTC, by 写代码的flanker); Bilibili could not be reached from the research environment on 8 Nov 2026, so the description was read from the researcher's saved copy of the video data made the same day (2,182 views at that time, observed; not a metric). The researcher's notes also quote a comment under the video giving the Claude version's source and play links; that comment could not be re-opened. The repository was cloned on 8 Nov 2026: 11 commits on 6 Sep 2026 (Beijing time), 10 with a Claude Fable 5.1 co-author trailer; the commit author name is not the account name, so only the handle is used. The live page was opened on 8 Nov 2026 (title 珊瑚海海战 · Coral Sea, page language zh-CN). No share of AI-written code is stated. Gameplay, scenarios and rules are from the README and design document; the game was not played. The repository shows no licence file. The video does not say whether the developer worked alone. The sister game CONTACT (Codex version) is a separate record; the two are different games, not versions of one build. Release date: the video is the first public mention found; the GitHub Pages deployment date was not read. The video says the agent built the games “晚上” (at night); the commits are time-stamped 10:37 to 16:10 UTC+8 on 6 Sep 2026, so the overnight build time is the developer's description and is not confirmed by the commit times.
Development history
All eleven commits are made in one day (Beijing time), from project start to an end-to-end-tested release; ten carry a Claude Fable 5.1 co-author trailer.
ObservedGitHub (flanker)The developer publishes a Bilibili video presenting this game and its Codex-made sister game CONTACT, with the source code public.
DeveloperBilibili (写代码的flanker)
Game performance
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Browser (official site)
Free in the browser; a static page with no account and no back end.
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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 |
|---|---|---|---|
| 珊瑚海海战！我用 GPT-6 和 Fable 5.1 做了两款网页战棋游戏 Bilibili (写代码的flanker) · Chinese (Simplified) | Social post | Sep 7, 2026 | Nov 3, 2026 |
| flanker/coral-sea-game (README) GitHub (flanker) · Chinese (Simplified) | Repository | Not confirmed | Nov 3, 2026 |
| flanker/coral-sea-game — design document and commit history GitHub (flanker) · Chinese (Simplified) | Repository | Not confirmed | Nov 3, 2026 |
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