CAPTCHAs now run Doom – on nightmare mode

January 3, 2025 TH Author

Though the same couldn’t be said for most of us mere mortals, Vercel CEO Guillermo Rauch had a productive festive period, resulting in a CAPTCHA that requires the user to kill three monsters in Doom – on nightmare mode.

The Completely Automated Public Turing test to tell Computers and Humans Apart is a challenge-response authentication scheme that presents people with a puzzle or question that a computer supposedly cannot solve.

This started in 1997 as a series of distorted letters and numbers, later evolving into image verification requests, then a more background process to identify low-risk human users under Google’s reCAPTCHA implementation. The technology is typically used to protect websites from being flooded with bot traffic.

However, as demonstrated in a 2023 study, CAPTCHA’s days are numbered as an effective bot defense because bots written for the purpose of beating CAPTCHAs can do it much quicker and more accurately than humans these days.

Announcing his latest innovation on New Year’s Eve, Rauch’s Doom CAPTCHA adds to a lengthy list of notable (and more serious/useful) feats, including authorship of Next.js, Mongoose, and Socket.IO, among other open source projects. The Doom CAPTCHA might take the title for most fun, though.

That is, if you can cope with Doom on nightmare mode, the highest difficulty, which makes the demonic enemies harder to kill and more aggressive. Your correspondent did manage it on the first try, once we remembered that it’s not immediately obvious how to strafe, and was left with a meager 19 percent health and a suitably bloodied and battered status bar face. Let us know if you fared any better in the comments.

While the CAPTCHA is a WebAssembly app, Rauch built the flesh and bones in v0, Vercel’s AI-powered web development agent announced in 2023, which generates projects from natural language prompts. You can see his process here.

Since most web users find even the most basic CAPTCHA an annoying hoop to jump through, we don’t see the nightmare Doom version gaining much traction outside the most sadistic devs implementing it as a joke or to intentionally annoy people.

The CAPTCHA’s legality is also potentially dubious. Only id Software’s Doom game engine is open source, the game data – maps, textures, sprites, etc. – are not, but all look present and correct here.

As The Register noted last year, OpenAI’s GPT-4 is capable of playing the game – badly. Give it a few years, though, and similar AI models may make mincemeat of Doom on nightmare. So, once again, CAPTCHA’s effectiveness as a bot defense comes into question.

As a tech demo for V0, however, it does the job. ®