Yes, This Christmas Tree Ornament Can Run Doom

“But can it run Doom?” is now more of a joke than anything else, but it used to be a serious question. Like Crysis in the late aughts, Doom was once a game that you needed a decent computer to play — it wasn’t going to run on that old Commodore 64. Doom hit the market in 1993, right around the time when it started to become common for users to build their own IBM-compatible PCs using standardized parts. That’s why it makes sense that Spritemods used an IBM PC as the model for this Christmas tree ornament that does, in fact, run Doom.

This is special, because the ornament is tiny and self-contained. Its “monitor” has a screen that is only 0.96” on the diagonal. And it is actually playable, too. The player can use a Bluetooth keyboard and mouse (or gamepad) to control Doomguy and blast demons. Many of these super small Doom projects simply run the demo to eliminate the need for input, so it is greatto see that this ornament not only runs Doom, but also makes it playable.

To make all of this work, Spritemods had to design his own custom PCB to fit into the little 3D-printed enclosure. Off-the-shelf development boards would be too big once one added all of the necessary components, so Spritemods had to get creative to fit the space. They used an ESP32-C2-Wrover-02 microcontroller, which has more memory accessible than the standard ESP32. The PCB also contains a lithium battery charger/booster module, I2S audio amplifier, and connections for the LCD screen, speaker, power switch, and USB charging port. That speaker is tiny, but enough to make the sound effects and music tracks audible.

Normal versions of Doom would still require too much RAM to run on this ESP32, so Spritemods used the GBADoom port that is optimized to run on a fraction of the memory. Spritemods also converted the propriety .mus music files to the open .imf format, which can play through an OPL emulator running on the ESP32.

The result is truly impressive. This may not be the smallest playable Doom hardware in existence, but it has got to be pretty close. And Spritemods could have made it even smaller if they weren’t trying to model the case after an IBM PC. We can’t think of a better ornament to celebrate the Christmas spirit.