Chessive
A card-and-board duel on a 5×5 grid where cards name the piece you move and both sides reveal at once; its developer says Claude Code built the trial version in about three days.
Links go to the official store or developer page. Last verified Nov 3, 2026.
Where to play
Every platform this game is on. Links are checked against official sources; we never host or mirror games.
- View demo on BrowserBrowserDemo · Trial version (試遊版); rules, art and modes are still being adjusted from player feedback.Free
Runs in a desktop or mobile browser. No download.
Browser (no download) · Mobile · Official link verified Nov 3, 2026.
About Chessive
A free browser game, currently a trial version, that mixes a card game with a shogi-style board. Each side has a King, a Rook, a Bishop and two Pawns on a 5×5 board. Every round both players pick one card and reveal it at the same time: the card only names which piece may move, and you choose where it goes within that piece's fixed moves. Because both sides move together, a target can slip away, and when two pieces enter the same square the holder of the priority star, which alternates each round, wins. Kings cannot be captured; an attack takes one of the King's three lives, and bringing the enemy King to zero wins. Other cards let you swap, reinforce, advance all Pawns at once or promote a Pawn, a Pawn that reaches the far row scores toward damaging the enemy King, and each deck holds a single Knight card that lets a piece jump like a shogi knight once. You can play the computer at four levels, play online by random match or with a room code, or learn in an eight-lesson tutorial taught by the King. It runs on phones and PCs with no install, in Japanese or English. Card art is placeholder pixel art and the music and sound effects are synthesised in code. The developer says the rules were worked out in discussion with OpenAI's GPT and the game was implemented with Claude Code, in about three days from idea to release.
How it was built
VerifiedThe developer's Qiita devlog says the implementation was done with Claude Code. The developer handed Claude Code the Markdown rule draft and asked whether it could be implemented for a playtest. Day 1 produced the rules engine, the computer opponent, pixel art and music, with computer-vs-computer matches to check balance; day 2 fixed what came up in play and added the online match server and deployment to an existing server; day 3 added the tutorial, attack effects, phone support, SEO, icons and a trailer. The developer describes a loop of playing, giving one-line feedback (such as that the Rook and Bishop looked too alike) and seeing it fixed within minutes. The result is about 5,300 lines of plain JavaScript without a framework or build step, plus a Node.js + ws match server. Before implementation the rules were debated with OpenAI's GPT, which the developer writes as “GPT（Codex）”; it proposed ideas, drew pictures of them and wrote the draft, while the developer rejected options and chose the final rules.
Design by debate, then fast playtest iteration. The developer started with a vague idea, a chess-like board game driven by cards, and argued it out with GPT, rejecting a pre-announced-checkmate rule as not exciting and a clash-card system as too much like rock-paper-scissors before settling on cards that name only the piece to move, plus a single Knight card as the surprise. The agreed draft, including a tuning table, became the spec for Claude Code. The rules engine is kept separate from the display, so the same file drives the screen, the computer opponent, automated tests and the server, which checks every online move against its own list of legal moves. Balance changes were tested with hundreds of automatic computer-vs-computer matches; the developer reports, for example, that the first “strong” opponent lost to the “normal” one 79–102 until its prediction of the opponent was loosened and it was made to read one move further for its ten strongest candidate moves, after which it won 189–84. The art and sound are made in code as placeholders meant to be replaced later.
- Engine / framework
- None (plain JavaScript in the browser; Node.js + ws match server)
- Languages
- JavaScript
- Team size
- Not disclosed
- Initial build time
- About 3 days from idea to public trial versionDeveloper ReportedQiita (mitsuoL)
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- Not disclosed
“ルールの議論は GPT（Codex）と、実装は Claude Code と一緒にやりました。アイデアから公開まで、だいたい3日です。”Verification notes: AI use from the developer's Qiita devlog of 18 Oct 2026, which links the game; the game page credits the trial version to mitsuoL, the same name as the Qiita author. Codex is not listed as a tool: the developer writes “GPT（Codex）” only for discussing the rules, not for writing code. The devlog does not say whether the developer wrote any code by hand, so no AI code share is recorded; it is classed as vibe-coded because the developer describes directing and playtesting while Claude Code implemented. The devlog does not say whether the developer works alone, so no team size is recorded. The trial was announced on 18 Oct 2026; the exact date it went live is not stated, so no release date is recorded. The devlog describes three computer levels; the game page now offers four (Easy, Normal, Hard, Master). The devlog says the game shares a server with the developer's separate Gungi-style game on the same domain; that game is not part of this record. The devlog mentions a trailer made for stores such as Steam, but we found no store listing. No public player counts were found. No source mentions generative AI running in the game.
Development history
The developer announces the free trial version on Qiita, about three days after the idea, with a devlog on how it was made.
DeveloperQiita (mitsuoL)
Game performance
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Browser (official site)
Free in the browser with no install; no payments found on the site.
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
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Sources
| Source | Type | Published | Accessed |
|---|---|---|---|
| Chessive｜カードで駒を動かす無料ブラウザ対戦ゲーム mitsuoL · Japanese | Official site | Not confirmed | Nov 3, 2026 |
| 「チェス×カードゲーム」をAIと議論して3日でブラウザ対戦ゲームにした話【Chessive】 Qiita (mitsuoL) · Japanese | Devlog | Oct 18, 2026 | Nov 3, 2026 |
| Official game page (language check) mitsuoL | Official site | Not confirmed | Nov 3, 2026 |
