Codex Mortis is a 100% AI-made roguelite bullet hell - and it's proving divisive as hell too

'Vibe coded' over three months using AI, including GPT for creating the art, and 'animations are a shader written by Claude Code' we're told.

Codex Mortis is a 100% AI-made roguelite bullet hell - and it's proving divisive as hell too
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Tech Reporter
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TL;DR: Codex Mortis takes pride in being the "first 100% AI-generated playable game" and it's a necromantic survival bullet hell which has polarized the gaming community as you might imagine. It's available to play as a Steam demo for those who want to test the waters of what a fully AI-made game might be like, but there are plenty who wouldn't go near it with a 10-foot skull staff.

You want a PC game that's 100% been created by AI? No, neither do I, but we've got one, and it's a bullet hell roguelite called Codex Mortis.

PC Gamer picked up on the game, which is still under development, but it's on Steam and there's a demo of Codex Mortis available if you dare to try it.

In a press release, the developer (Crunchfest) states: "Crunchfest today released the playable demo for Codex Mortis, a necromantic survival bullet hell that makes gaming history as the first 100% AI-generated playable game. Plan your build, combine spells into synergies, and watch the battlefield erupt in beautiful chaos. The demo is available now on Steam for solo or local co-op play."

In a Reddit post, the developer further explains how the game was made: "It's pure TypeScript. I use PIXI.js for rendering, bitECS for the entity-component-system backend, and Electron to wrap it as a desktop app. The whole thing was vibe-coded with Claude Code (mostly Opus 4.1 and 4.5)."

So, if you were wondering how this was achieved, there you have it.

I haven't played the demo of Codex Mortis, so I won't judge it - I hate these kinds of bullet hell games anyway, they're totally not for me - but the reaction it's getting is predictably mixed.

On the one hand, it's not a trivial effort to make a game even if you are leveraging AI to do all of the heavy lifting, and there's some admiration of that. It took three months to complete the project (as it stands) outside of the dev's 9-to-5 job.

On the other hand, there's enough AI slop out there already, and we don't want an avalanche of shovelled-out games joining all that.

There's some criticism of the art direction (GPT was used here) feeling rather all over the place - and on that subject, the developer says that "maintaining a consistent art style was tricky, but GPT managed to remember what visual style I liked and kept it consistent across different sessions".

Also, the AI-generated promo video that accompanies the demo is not going down well (and I can see why - it wasn't a good idea).

Above all, though, the developer observes that the most important takeaway from this project for them was: "Compared to traditional app development, this is way less mentally draining - kind of like giving an exoskeleton to a construction worker lol."

The concern is, of course, that it leads to a product which has no soul, rather like the aforementioned exoskeleton.