DOOM Runs On… What?!

There was once – and still is – a first-person shooter game called DOOM. Now it runs on… the most absurd platforms possible.

DOOM on… Really Odd Platforms

Sometime in the early 1990s, my then-housemates brought home a shoot-em-up game called DOOM for PCs. ^[1] I played it a little bit, since initially it was about shooting monsters only. But quickly it became about shooting human-looking things and… well, that pretty much squicked me out. (I have a famously low tolerance for depictions of violence in media.)

At first there was a minor sport of making DOOM .wad files (world definitions, more or less) to make the game appear to be happening in some interesting location. I remember seeing one played on the grounds of Trinity College, Cambridge, in the UK, for example ^[2], and other places.

Famously, it was also once ported to run on a pregnancy test. ^{[3] [4]} Yes, pregnancy tests contain a (tiny) computer. Yes, people are crazy enough to do that. It’s only a 128x32 monochrome screen, so you must be extremely determined to play it that way. (No word on whether the pregnancy test is good for anything afterwards, either.)

There’s even a subreddit (r/itrunsdoom) devoted to this peculiar sport.

Ok… So What Have the Nerds Gone & Done Now?

Well, that’s all good sport. Sort of.

But now comes word that DOOM has been ported to run in… a PDF file! ^[5]

How can that possibly be? PDF (Adobe “portable document format”) is a data format for documents to be displayed, isn’t it? Well, like many rich document formats (lookin’ at you, Microsoft Word) they eventually embrace executable content, animations, external links, that sort of thing.

First Word had macros, and those were a security nightmare because every Word document became a possible vector for infection by malware. That got sort of handled & sort of ignored. Later, Adobe in particular added the capability to put the dreaded Javascript we all hate so much into PDF documents. Even some web browsers support this.

So it was only a matter of time before someone took cross-compilation to the highest levels of insanity, and got DOOM to compile to sufficiently elementary things that it could be put in a PDF file. If that PDF file is loaded in a reasonable viewer (e.g., Acrobat or, apparently, the built-in viewer in Chrome), then you can play DOOM. (Sorta.)

How long until inter-office PDF documents contain hidden games? I bet less than 15 minutes, i.e., it’s already happened.

That’s unpredictable fun. But the next move was more or less entirely predictable: the same person got a trimmed-down version of Linux to run in a PDF ^[6] by means of a RISC-V emulator!

This is… both silly and serious. Not only can you smuggle in software under cover of PDF, you can drag in a whole dang operating system.

How long until this is a malware attack vector? Wanna bet it’s already being tried?

The Weekend Conclusion

Why in the world do people do things like this?

• On the one hand, I get the absurd humor.

  Surrealism is always an excuse! (At least the first time.)

• On the other hand, this is a nontrivial amount of effort! It might be an attempt at an arcane and absurd demonstration that Acrobat and other PDF viewers have not even the slightest hope of ever being secure?

  What will the world be like when viewing a document must be eyed skeptically as a possible infection vector? People open PDF documents without a thought, and will continue to do so no matter what security experts tell them.

  Do you really trust Adobe to have properly, thoroughly, and suspiciously sandboxed this so software running in a PDF viewer can’t get out? Of course they’ll say so, but how do you know you can take their word for it?

As a friend – in fact one of the friends who introduced me to DOOM in about 1993 – said this morning:

It will turn out that our entire reality is a simulation running in a giant PDF document being read by a bored Boltzmann brain, while sitting on a Boltzmann toilet.

Cynical, sure. But it makes about as much sense as anything else.

This was a weird timeline even before Trump began our self-inflicted destruction and demise.

(Ceterum censeo, Trump incarcerandam esse.)

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Notes & References

1: Wikipedia Editors, “Doom (franchise)”, Wikipedia, retrieved 2025-Jun-30. ↩

2: S McCrea, S Wall, && E Papavassilopoulos, “The Unholy Trinity”, DoomWorld web site, downloaded 2025-Jun-30. ↩

3: S Schroeder, “Guy runs ‘Doom’ on a pregnancy test and wait, what?”, Mashable, 2020-Sep-07. ↩

4: Nev’s Tech Bits, “@Foon Got Doom Running on a Pregnancy Tester”, Nev’s Tech Playground & Archives YouTube channel, 2020-Sep-07. ↩

5: adling2210, “doompdf”, GitHub repository, downloaded 2025-Jun-30. NB: In the bio for this repository, adling2210 claims to be a high school student. Bet this shows up on a university application!

You can (attempt to) play it here. ↩

6: adling2210, “linuxpdf”, GitHub repository, downloaded 2025-Jun-30. ↩