隔壁の外
A 2D side-scrolling action game with three stages and three bosses; the developer says Claude Code wrote all 15,000 lines and that they never read the code.
Official site hawkclaws.itch.io, verified Nov 3, 2026. The developer's own itch.io page, linked from the developer's Zenn article.
Where to play
Every platform this game is on. Links are checked against official sources; we never host or mirror games.
- Play free — itch.ioitch.ioReleasedFree
Plays in the browser on itch.io. No download.
Browser (no download) · Official link verified Nov 3, 2026.
About 隔壁の外
A free 2D side-scrolling action game in Japanese that runs in the browser with no install. The developer, HawkClaws, describes it as three stages and three bosses, about two to three hours from start to finish. In a postmortem on Zenn, the developer says they wrote none of its roughly 15,000 lines of GDScript, 20 Python scripts and 24 automated checks: Claude Code wrote all of it, and the developer did not read the code either. Instead the developer steered through twelve Markdown documents of more than 5,000 lines, most of them also written by the AI, by stating direction out loud, saying when results were wrong, reporting bugs as symptoms, and having lasting rules recorded, such as enemies winding up before they strike and no pitfalls. The article's main point is a failure: the automated checks stopped at the ninth of 24 for two days without anyone noticing, because a run that stops shows no red lines. The itch.io AI disclosure ticks Code, Graphics, Sounds and Text.
How it was built
Partially verifiedThe developer's Zenn article says all of the roughly 15,000 lines of GDScript, the 20 Python scripts and the 24 automated checks were written by the coding agent Claude Code, that the developer wrote none of it and did not read it, and that the twelve Markdown design documents (over 5,000 lines) were mostly written by the AI as well. The developer's part was stating direction, rejecting results, describing bugs by their symptoms and asking for lasting rules to be written into the documents. The itch.io page says “Made with Claude Code.”
- Developeritch.io page: “Made with Claude Code.”; AI disclosure: AI Assisted, with Code, Graphics, Sounds and Text ticked. — itch.io
Document-driven development without writing or reading code, per the developer's Zenn article. Twelve Markdown documents (concept, game spec, technical setup, asset pipeline, open questions, workflow, visual direction, roadmap, prompts, a hand-over document and two character designs) were read and updated by the agent; lasting decisions were kept in a table with the developer's original words. Feel was judged by playing; numbers were checked by 24 agent-written probes (movement, jump height, stage traversal, enemies stopping at edges, assets loading) taking 8 to 10 minutes a run. The developer lists the mistakes this missed: a check that stopped at probe 9 for two days, a validation script that broke two correct assets, and a wait loop that spun for 109 minutes. The most useful document was a 600-line hand-over note listing pitfalls for the next session.
- Engine / framework
- Godot
- Languages
- GDScript, Python
- Team size
- Not disclosed
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- ~100% of shipped codeDeveloper ReportedZenn (HawkClaws)
Verification notes: AI use from the developer's Zenn article (published 18 Sep 2026, 13:33 JST; updated 23 Sep) (“自分で書いた行は 0 です。全部コーディングエージェント（Claude Code）に書かせました。”) and the itch.io page (“Made with Claude Code.”; AI disclosure Code, Graphics, Sounds, Text). The 100% AI code share is the developer's statement of zero self-written lines; line counts are the developer's and not checked. The article mentions generated images being returned to the agent but does not name the services used for graphics or sound. Stages, bosses and play time (2 to 3 hours) from the article; the itch.io page has no game description, and we did not play the game. No release date is shown on the itch.io page, so none is recorded; the Zenn article is the earliest dated mention we found. The article is tagged 個人開発 (solo project) but does not otherwise say whether anyone else was involved, so team size is not recorded. The itch.io page and title are in Japanese; credits there list the Godot Engine (MIT) and Noto Sans JP. The book on BOOTH that the page mentions is about the making of the game and is not the game. No ratings are shown on the page. The developer's location is not stated.
Development history
The developer publishes a Zenn postmortem on making the game with Claude Code, linking the free browser version on itch.io.
DeveloperZenn (HawkClaws)
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.
itch.io
Free in the browser with no install (HTML5).
No public metrics recorded for this listing.
Not publicly available: itch.io rating, 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 |
|---|---|---|---|
| AIに15,000行書かせてゲーム1本出したが、緑だと思ってた検証は9番目で止まっていた Zenn (HawkClaws) · Japanese | Devlog | Sep 18, 2026 | Nov 3, 2026 |
| 隔壁の外 by HawkClaws itch.io · Japanese | Store page | Not confirmed | Nov 3, 2026 |
| Official game page (language check) HawkClaws | Official site | Not confirmed | Nov 3, 2026 |
