Report / Published 2026-11-02

Anthropic added a Claude rule against recreating existing games

Anthropic added two sentences to Claude Code's prompt on Opus 5.5 telling it not to recreate a specific existing game, as PC Gamer and IGN report. The change follows a Steam Next Fest in which showcased demos doubled over the previous event, with AI-assisted games accounting for most of the increase, and several studios cancelled public demos.

(See the reader poll and source context below).

Anthropic added two sentences to Claude Code's prompt on Opus 5.5 telling it not to recreate a specific existing game, after Steam's demo flood and cancelled demos.

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What do the sources establish?

Recorded source context. No verified social reaction quotes or aggregate vote results are supplied.
Platform / SourceCore Stance / QuoteEngagement MetricTimestamp
Anthropic Blocks AI Game Clones in Claude Opus UpdateReported context: [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]Not recordedNot recorded
Anthropic updates Claude to 'steer it away' from letting users clone games following weeks of Steam being inundated with AI slopReported context: [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]Not recordedNot recorded

THE SHORT VERSION

  • Anthropic added two sentences to Claude Code's prompt on Opus 5.5 telling it not to recreate a specific existing game, as PC Gamer and IGN report.
  • The change follows a Steam Next Fest in which showcased demos doubled over the previous event, with AI-assisted games accounting for most of the increase, and several studios cancelled public demos.
  • IGN says it is unclear what prompted the change and how much impact it will have, while Valve has said it will not act as a gatekeeper on which tools developers use.

Two sentences added to the Claude Code prompt

Anthropic added two sentences to Claude Code's prompt on Opus 5.5 that steer the assistant away from rebuilding a specific existing game. Addy Osmani, a member of Anthropic's technical staff, explained the change in a reply to a post by X user Chasm, and both PC Gamer and IGN quote him. Osmani wrote: "We added two sentences to Claude Code's prompt on Opus 5.5 to steer it away from recreating someone else's specific game because using Claude to infringe IP is against our usage policy."

The rule itself, as both outlets print it, reads: "Do build original games, games in a genre, and games from the user's own designs and assets. Do not build a recreation of a specific existing game, even if it is renamed or called original." IGN relays a post from Chasm saying the rule arrived around 27 October under a flag called tengu_heron_brook and that no setting turns it off. Neither outlet reports Anthropic dating the change itself or publishing the rule anywhere outside the prompt.

The Steam flood that came first

The update follows weeks in which Steam filled with low-effort releases made with AI tools. PC Gamer reports that the most recent Steam Next Fest saw the number of showcased demos double over the previous event, with AI-assisted games accounting for most of that increase. IGN ties the complaints to the same festival, writing that players said their feeds were full of clones of existing games and of titles that had only just released demos of their own.

Valve has acknowledged the problem without banning the tools. PC Gamer reports that at Steam's Indie Connect event, Valve's Tom Giardino said the company does not want "to be gatekeepers telling developers which tools they should or shouldn't use." IGN reports that Valve said it would be "thinking about how to solve this problem." Neither outlet reports a new Valve policy, and PC Gamer notes that Giardino gave no specific answer beyond calling a smarter, more dynamic platform the starting point of the company's approach.

Studios pulled their demos instead

The damage landed on small teams whose demos could be read as code. PC Gamer reports that several studios cancelled planned public demos for fear that the code would be reverse engineered into clones. IGN names two: Alliance Arts, the developer of Drunken Goddess Reflux, and Who You, both of which dropped Steam demo plans in favour of private playtests.

That is the part of the story the rule speaks to. A public demo is also a public build, and a model that can read code can describe how a game works. PC Gamer reports that Opus 5.5 has proved adept at reverse engineering, with effects ranging from rapid decompiling of old console games to the PS5 being jailbroken. The same capability that helps a team port an old title also lets someone else rebuild it.

The same capability seen as volume

Anthropic's change is one intervention in a year of argument about where generated code belongs. This site's report on Roblox's quarterly letter counted 70,000 games published through its Build tool in five months, which is the same capability measured as output. That report describes a platform treating the resulting flood as a selling point rather than as a problem to be filtered.

What separates that case from the Steam complaints is consent and scale. Roblox describes tools applied to its own platform and its own pipeline. The complaints concerned releases that copied other people's games, sometimes days after a demo appeared. PC Gamer draws the line at lifting a codebase wholesale rather than riffing on ideas, and notes that simple designs such as Vampire Survivors, Balatro and Peak have spawned endless imitators without that being the same act.

What the rule does not settle

What the rule changes in practice is not established. IGN states that whether a specific event or reason prompted the change is unclear, and that how much impact it will have remains to be seen. The rule is an instruction inside a coding assistant rather than a filter on what reaches a store, and neither outlet reports a detector, a watermark or a review step behind it. The site's report on the Skyblivion volunteer lawsuit covers the same question from the other side, where the people rebuilding an existing world are unpaid fans rather than a model.

Osmani's reply also marks the edge of the promise. He wrote that original games, genre games and games built from a user's own designs and assets are meant to keep working, that Anthropic will continue to iterate to strike the right balance, and that anyone whose own work is refused should send it to him. That is an invitation to report false positives rather than a published policy, and neither outlet describes a process beyond it.

What would show the rule working

Three signals would show whether the rule matters. The first is whether developers report fewer clones in the weeks after the update. The second is whether Valve moves at the store level, where a clone that already shipped stays on sale; this site's report on Croc 2's Switch remaster shows the licensed version of the same act arriving with a publisher behind it. The third is whether the rule becomes something a user can read or appeal outside a reply on X.

For players the practical question is narrower. A clone that already shipped stays on sale, and a line inside a coding assistant does not remove it. The rule affects the next attempt, and only for people using Claude. PC Gamer's closing argument is that simple games have always been imitated, and that the difference now is how quickly and how cheaply a copy can be produced. Whether a prompt line changes that calculation is the thing to watch.

Sources & reporting limits

  1. Anthropic Blocks AI Game Clones in Claude Opus Update
  2. Anthropic updates Claude to 'steer it away' from letting users clone games following weeks of Steam being inundated with AI slop
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