Latest Doom port runs inside a PDF document, but performance is limited

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The big picture: Doom, the original first-person shooter for DOS by id Software, was released in 1993. Despite being over 30 years old, the game continues to inspire resourceful (and somewhat crazy) developers to run its code in some of the most unusual computing environments imaginable.

We can now add PDF documents to the ever-growing list of “things” that can run Doom. A high school student interested in programming and cybersecurity developed the DoomPDF project, providing yet another example of how killing cacodemons on Mars has become a truly universal pastime, no matter the technology used.

Developer “Ading2210” was able to create DoomPDF because the PDF standard supports JavaScript code. Adobe Acrobat implements the full specification of the PDF JS library, the programmer explained, allowing for some truly amazing feats, including 3D rendering, hardware detection, and more. However, DoomPDF relies on the JavaScript implementation in modern web browsers, which feature a more limited “PDF engine” and API support.

Despite these limitations, Chrome and other Chromium-based browsers can perform “whatever computation we want,” Ading2210 said, with only minimal I/O interactions. The developer compiled Doom’s original C code with an older version of Emscripten that targets asm.js instead of WebAssembly. Inputs can be read through text fields and buttons, but “rendering” a fast-enough Doom graphics replica proved to be a much more challenging task.

DoomPDF can achieve a six-color monochrome output, which should be enough to provide a “legible” in-game representation on the screen. The Doom PDF port, which can be played on Chromium browsers, isn’t the most performance-optimized version of the game, though it could be considered “playable” if you’re obsessed enough.

Doom has been officially ported to game consoles, PC systems, different operating systems, mobile devices, and essentially every new computing platform developed since the 1990s. Even Doom Eternal, the latest entry in the Doom saga, includes the original “wad” files for Doom and Doom II, which you can load while chilling at the Doom Slayer’s fortress of solitude orbiting Earth.

Developer id Software released the source code for Doom in 1997, a choice that sparked a meme-like movement where programmers are trying to run the game on the most esoteric devices they can hack. So far, Doom has proven to run on CAPTCHAs, alarm clocks, GPUs, volumetric displays, AI models, and much more.