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A developer gave an AI model an open-ended brief to build its own stickman game. In one day, Claude Opus 5.5 produced BEATDOWN, a rhythm-based stick-figure brawler, and expanded it into a free ten-card Stickman Arcade with a stick-figure animator — roughly 24,500 lines of dependency-free JavaScript, with no hand-written code from the developer.

A developer who gave an AI model a deliberately open brief — build your own stickman game, no clone, no tutorial — ended the day with a ten-card Stickman Arcade: nine free browser games and a stick-figure animator, all written by the model itself. The headliner is BEATDOWN, a stick-figure brawler in which every attack is judged against a soundtrack generated live in the browser. According to the developer, the entire arcade was built by Claude (Opus 5.5) in one day, with no code written by hand.

BEATDOWN’s central mechanic is timing rather than speed. Every button press is judged against a beat, with on-beat hits dealing 1.5× damage. A streak mechanic called FOUR ON THE FLOOR rewards four consecutive on-beat hits with a bonus strike and shockwave, while a COUNTERPOINT system has enemies wind up on one beat and strike on the next, allowing a well-timed guard to trigger a counter. The soundtrack is generated in the browser, and better play adds musical layers, moving a Groove rank from MUTE up to FEVER. According to the project description, rhythm is a bonus rather than a requirement — off-beat play still clears waves, it simply deals less damage.

The roster comprises twelve original fighters, each built around a musical archetype — Drummer, Conductor, DJ, Bassist, Punk, Soprano, MC, Jazz Cat, Shredder, Virtuoso, Beatboxer and Producer. Each fighter has a passive ability, two specials, a cooldown skill and an ultimate called the DROP, for sixty abilities in total. Examples given include the DJ’s DROP, which cuts the band for two beats before hitting the whole stage, and the Shredder’s GUITAR SOLO, which fires a lick on every beat.

The arcade includes nine art styles — among them CHALK, RISO, PIXEL, BRUSH, BLUEPRINT and NOIR — that change how fighters, venues, hit effects and menus are drawn rather than just recolouring them. BEATDOWN offers seven venues with distinct rules, a TOUR mode with bosses, and a local VERSUS mode for two players on one keyboard or two gamepads, with a computer opponent that also plays on the beat. The remaining eight games, each on the same engine, include Stickman Dismount, Pose-Off, Beat Runner, Noir Heist, Band Defense, Stickman Boxing, Head Soccer and Beat Skate. The tenth card, Stickman Animator, lets users pose figures by dragging joints, build frames with ghosted neighbours, add in-between frames and export a looping GIF, sprite sheet or still.

According to the developer, the entire project is code: no image files and no audio files, with all visuals and sound generated at runtime. The codebase is described as roughly 24,500 lines of plain JavaScript with zero dependencies, including the animator’s own GIF encoder. The games are said to collect no data, with progress stored in the player’s own browser.

What This Says About AI-Built Software

The project is a data point in an ongoing debate about how much of the creative and technical work of software development AI models can now carry end to end. The developer’s role shifted from coder to director: answering questions, supplying screenshots of reference games and repeatedly asking for more. BEATDOWN was reportedly playable in under an hour and live on the site in under two, with the model then writing a shared game kit and engine guide before building the remaining eight games.

For readers outside game development, the arcade also demonstrates a practical pattern for small, self-contained web software: a single dependency-free JavaScript codebase that runs in any browser and on phones, with no assets to download and no data collection. If the claims hold up, the project shows an AI model handling game design, procedural art, procedural audio and even a GIF encoder — traditionally separate skills — in one continuous session.

How the Arcade Came Together

The project began with a deliberately loose brief, according to the developer: make your own stickman game, explicitly not a clone or tutorial project. The model’s first output was BEATDOWN. Over the same day, repeated follow-up requests expanded it into a full arcade: after the headliner, the AI wrote a shared game kit and an engine guide, then built the eight additional games and the animator on top of that foundation, keeping a consistent system of nine art styles across everything. The arcade is presented as ten animated cards on a single site, all free to play, with the chosen art style carrying across the whole collection.

“I gave an AI model a deliberately loose brief: make your own stickman game. No clone, no tutorial project, just its own take on a genre everyone knows.”

— Project developer (site author)

Claims That Remain Developer-Reported

The one-day build time, the roughly 24,500-line codebase, the zero-dependency claim and the statement that no code was written by hand all come from the developer’s own account and have not been independently verified. The site’s post also notes it was created with the assistance of AI, and the page contains affiliate advertising, so it has a promotional interest in traffic. The quality and performance of the games across different browsers and devices — particularly the procedurally generated audio and touch controls on phones — can only be assessed by playing them. It is also not documented how much iteration, prompt correction or discarded work occurred during the day, which affects how the build time should be interpreted.

Where the Arcade Goes From Here

The developer indicated the pattern of “kept asking for more” drove the arcade’s growth, suggesting further additions are possible on the shared engine. Nothing further has been announced. Readers can try the arcade itself in a browser or on a phone at no cost; the DAILY MIX mode, which serves the same seeded run to all players each day, is the component most likely to reward returning players. How the project holds up under real-world play — across devices, over longer sessions — will be the practical test of the build.

Key Questions

Who wrote the code for the Stickman Arcade?

According to the developer, all of the code — roughly 24,500 lines of plain JavaScript with no dependencies — was written by the AI model Claude (Opus 5.5) in a single day. The developer describes their own role as steering: answering questions and requesting more features.

What is BEATDOWN?

BEATDOWN is the headliner game: a stick-figure brawler in which every attack is judged against a live-generated soundtrack. On-beat hits deal 1.5× damage, better play adds musical layers, and a Groove rank climbs from MUTE to FEVER. It features twelve fighters with sixty abilities, seven venues and local versus play.

Do I need to be good at rhythm games to play?

No. The project description states that rhythm is a bonus, never a requirement — off-beat play still clears waves, it simply deals less damage and sounds less full.

What platforms do the games run on?

All nine games and the animator run in any modern browser, including on phones with touch controls. There are no image or audio files to download; visuals and sound are generated by code at runtime.

Does the arcade collect player data?

According to the developer, the games collect nothing, and player progress is stored locally in the player’s own browser. This claim has not been independently audited.

Source: Thorsten Meyer AI