A new roguelite called Codex Mortis is making a bold—and deliberately provocative—claim: it says it’s “the world’s first fully playable game created 100% through AI.” In an industry where generative AI is already everywhere, the assertion feels less like a quiet technical milestone and more like a flashing neon sign daring critics to look closer.
According to a Google survey, 87% of game developers now use AI in some capacity, whether for concept art, code assistance, or production workflows. But Codex Mortis pushes that trend to its extreme. Rather than treating AI as a tool, its developer claims AI was the entire pipeline.
Built Without a Traditional Engine
The developer, posting under the username Crunchfest3, shared details of the project on the AI game dev subreddit. Instead of using Unity, Unreal, or Godot, Codex Mortis was assembled using a custom stack:
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TypeScript as the core language
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PIXI.js for rendering
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bitECS for the entity-component-system backend
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Electron to package the game as a desktop app
All of this, Crunchfest3 says, was put together in roughly three months, using a process they describe as “vibe-coding.” The bulk of the programming was generated with Claude Code, primarily using Opus 4.1 and 4.5 models.
Visuals were generated using ChatGPT, while the game’s animations come from AI-written shaders, also produced via Claude Code. The result is a game that doesn’t just use AI assistance—it openly centers AI as the creator.
A Deliberately Confrontational Presentation
Codex Mortis is currently available only as a demo on Steam, but its marketing makes its intentions clear. The AI-generated cinematic trailer depicts a robed sorcerer vaporizing a demon labeled “AI antis,” positioning the game squarely in the ongoing cultural conflict over generative AI in creative industries.
That posture alone has ensured attention—but the game itself also reinforces the message.
A Familiar Game, With an AI Signature
At its core, Codex Mortis is a bullet heaven roguelite, heavily inspired by Vampire Survivors. Mechanically, it appears to hit many of the genre’s expected beats: waves of enemies, escalating power, and chaotic screen-filling combat.
Visually, however, it bears the unmistakable fingerprints of AI generation. The art style is muddy and indistinct, lacking the sharp visual identity that often separates standout roguelites from the crowd. Ironically, this sameness may be its most distinguishing feature—it looks exactly like what many people imagine when they hear “AI-made game.”
Still, by most definitions, Codex Mortis is a real, playable video game. That alone makes it noteworthy as a demonstration of what modern generative tools can assemble when pushed end-to-end.
Is It Really a “World’s First”?
The claim of being the first fully AI-generated game is difficult to verify. Projects like Doomscroll, a browser game generated using ChatGPT by hobby coder David Friedman, complicate the narrative. There are almost certainly other experimental titles that leaned heavily—or even entirely—on generative AI during development.
What may set Codex Mortis apart is intent and distribution. Releasing on Steam, potentially as a paid product, places it closer to the commercial mainstream than most AI game experiments. It’s less a tech demo and more a statement: this is what AI-driven game development looks like right now.
Progress, Provocation, or Both?
Whether Codex Mortis represents a genuine milestone or a controversial novelty depends on perspective. As a proof of concept, it demonstrates that generative AI can meaningfully contribute to—or outright replace—large portions of the traditional game development workflow.
At the same time, the developer’s pride in “vibe-coding” everything may strike some as less a triumph and more a warning. Efficiency and speed are undeniable, but questions around originality, artistic intent, and long-term sustainability remain unresolved.
Codex Mortis may not be the future of game development—but it is a clear signal that the future is already knocking, whether the industry is comfortable answering the door or not.
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