Developer releases Codex Mortis, claiming it's the first 100% AI-generated playable game

Developer Claims Historic Milestone with Codex Mortis

A developer known as Crunchfest, also going by Grolaf, has released what they're calling the world's first fully playable game created 100% through AI 1

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. Codex Mortis, a necromantic survival roguelite bullet hell inspired by Vampire Survivors, was completed in just three months outside the developer's regular 9-to-5 job 3

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. The AI game is now available as a demo on Steam, where it describes itself as offering players the chance to "mix five schools of dark magic, unleash devastating spell synergies, and raise undead armies" in solo or local co-op modes 2

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Inside the AI-Driven Process Behind the Game

The AI game development approach for Codex Mortis bypassed traditional game engines entirely. Crunchfest explained on the AI game dev subreddit that the project uses "pure TypeScript" with PIXI.js for rendering, bitECS for the entity-component-system backend, and Electron to wrap it as a desktop app 1

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. The entire codebase was "vibe-coded" using Claude Code, primarily with Opus 4.1 and 4.5 models, while ChatGPT generated all the artwork 2

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. Even the game's animations rely on a shader written by Claude Code rather than traditional character animation techniques 1

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The developer acknowledged several challenges with using generative AI tools exclusively. "Maintaining a consistent art style was tricky, but GPT managed to remember what visual style I liked and kept it consistent across different sessions," Crunchfest noted 2

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. Technical hurdles included integrating Steam with Electron, which proved less smooth than with Unity or Unreal, and initial attempts with Tauri that failed entirely 2

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Gaming Community Responds with Overwhelming Skepticism

The 100% AI-generated playable game has triggered a divisive response across gaming communities. Steam discussion forums filled with threads titled "Lmao, this looks like ass," "Garbage AI slop," and "Dangerous slippery slope" 2

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. The game's visual presentation features what critics describe as a "muddy, indistinct art style" riddled with AI artifacts that distinguish it unfavorably from its inspirations 1

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. An AI-generated cinematic trailer showing a robed sorcerer vaporizing a demon labeled "AI antis" added fuel to the controversy 1

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Some observers question whether Codex Mortis represents intentional rage bait designed to court controversy 4

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. "This looks like a 1 year old made it by typing random stuff in an AI generator," one YouTube commenter wrote 4

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. Others noted the game's striking similarity to Vampire Survivors, with some suggesting it could be mistaken for a mod 4

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What This Milestone Means for the Industry

Whether Codex Mortis truly represents a milestone or merely contributes to the growing pile of AI slop remains contested. The game's claim as a world's first is difficult to verify—hobby coder David Friedman's Doomscroll is a browser game generated using ChatGPT, and numerous other projects have explored similar territory 1

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. What may distinguish Codex Mortis is its release on Steam as a potentially paid product 1

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The developer emphasized that "compared to traditional app development, this is way less mentally draining - kind of like giving an exoskeleton to a construction worker" 2

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. This perspective highlights the ethical implications and practical considerations as AI tools become more prevalent. A Google survey estimated that 87% of game developers are already using generative AI in some capacity 1

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, suggesting that while full AI game development may be novel, partial integration is already standard practice. Whether Grolaf's project represents a strategy to attract AI enthusiasts or simply attention-seeking behavior before developing "a real game," the negative reactions underscore deep-seated concerns about quality, originality, and the future direction of game development 4

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