When you think of PDFs, you probably think about work documents, contracts, and static images. The file format is not known as a gaming platform, but that's exactly how one developer decided to use it. Thomas Rinsma, a security analyst, created a fully functional version of Tetris within a PDF file. While I don't think the game, dubbed pdftris, will become a staple for PC gamers, it is an interesting hacker project that shows the capabilities of PDF files when used in a unique way.
You can play Tetris within a PDF by opening this file in a compatible browser. Rinsma notes that Firefox and all Chromium browsers are supported, though I had a better experience in Chrome than within Edge. That's likely due to the fact that Edge uses Adobe Reader, which is "not compliant in several ways," according to Rinsma.
Here's a working game of Tetris inside a PDF. Even has keyboard controls (by typing WASD in an input box). Plus, upon game-over you can "save" your score by printing the page ;)https://t.co/YrOInaHOUYShould work in most browsers (built for pdfium/PDF.js). pic.twitter.com/n4CPcitzz9January 5, 2025
The game does not exactly run smoothly, which is hardly a surprise. When I loaded pdftris in Edge the framerate of the game was so low I couldn't play it correctly. The game ran better within Chrome but showed some black lines across my screen. But smooth gameplay isn't what a project like pdftris is about.
Getting Tetris within a PDF was a fun project that also presented a challenge to overcome. Both PDFium, Chromium's PDF reader, and PDF.js, Firefox's PDF reader, use different engines.
"It was a bit tricky to find a union of features that work in both engines, but in the end it turns out that showing/hiding annotation "fields" works well to make monochrome pixels, and keyboard input can be achieved by typing in a text input box," explained Rinsma in a post on Hacker News.
Following feedback from users and those interested in the project, Rinsma shared a blog post about the project. There, they answer the first question I imagine many people will ask, "why would you make Tetris within a PDF?" The short answer from Rinsma is "why not?" Inspiration for the project came after Rinsma realized that PDF engines in modern desktop browsers support JavaScript and some I/O primitives.
You can also check out the project on GitHub to see the code used to make keystroke-entry within a text field that allows you to control the following blocks within pdftris.
In case you were wondering, yes, a PDF can be used to run Doom. Rinsma managed to get the classic game working within a PDF after some tinkering.
