Codex Mortis is a new game similar to Vampire Survivors, and its creator Grolaf, also known as Crunchfest, claims that everything in it was created using artificial intelligence. From the images and code to the music—everything is 100% the work of AI. Development took three months, and a free demo is now available on Steam.
How the Game Was Made Without a Game Engine
Grolaf did not use any traditional game engine. Instead, he opted for TypeScript for the code, PIXI.js for rendering, bitECS for the entity-component system, and Electron to package it as a desktop application. He created the images in ChatGPT and replaced animations with a shader made by Claude Code, specifically versions Opus 4.1 and 4.5. He started with a prototype to test whether it was even possible, then continued developing it. He said that maintaining a consistent visual style was difficult, but GPT remembered what he liked and maintained consistency across different sessions. The character animations did not work out, so he replaced them with a shader-based waving effect. Steam integration was complicated; he tried Tauri first, but it did not work, so he switched to Electron. He described the entire process as less exhausting than traditional development.
The Game vs. the Players
In Codex Mortis, death is your weapon. Players combine five schools of dark magic, unlock spell synergies, and summon armies of the undead in bullet-hell style. It can be played solo or cooperatively, with endless build possibilities. The game has a gothic fantasy atmosphere where you survive amid a hail of bullets. Reviews are mixed, with one saying that the demo is worth the price because it is free.
Threads with titles such as "Lmao, this looks like ass", "Garbage AI slop", "Dangerous slippery slope", and "100% AI generated - don’t buy and don’t support this" have appeared on the Steam forums. Players dislike that the game looks generic and uninteresting, and they see it as a threat to the gaming industry. Some comments on Reddit’s r/aigamedev were deleted, but overall there is less hostility there. One thread title asks: "Why everyone is butthurt about IA in game development?" Grolaf himself admits that the game was created partly as a provocation, which is already evident from the trailer. Artificial intelligence is frequently used in game development, but Codex Mortis is the first game in which AI made everything from scratch—textures, models, sounds, characters, and shaders—while a human merely assembled it all with the help of AI tools.
Sources: news.aibase.com and eurogamer.net
