Programmer Gets Doom Running On a Space Satellite

An Icelandic programmer successfully ran Doom on the European Space Agency's OPS-SAT satellite, proving that the iconic 1993 shooter can now run not just everywhere on Earth -- but in orbit. ZDNet reports: Olafur Waage, a senior software developer from Iceland who now works in Norway, explained at Ubuntu Summit 25.10 how he, a self-described 'professional keyboard typist' and maker of funny videos, ended up making what is perhaps the game's most outlandish port yet: Doom running on a real satellite in orbit, the European Space Agency (ESA) OPS-SAT satellite. OPS-SAT, a 'flying laboratory' for testing novel onboard computing techniques, was equipped with an experimental computer approximately 10 times more powerful than the norm for spacecraft. Waag explained, 'OPS-SAT was the first of its kind, devoted to demonstrating drastically improved mission control capabilities when satellites can fly more powerful onboard computers. The point was to break the curse of being too risk-averse with multi-million-dollar spacecraft.' (The satellite was decommissioned in 2024.)

Running Doom in orbit was partly a challenge of portability and partly a challenge of the limitations of space hardware and mission control. The on-board ARM dual-core Cortex-A9 processor, while hot stuff for space computing hardware (which tends to be low-powered and radiation-hardened), was slow even by Earth-bound standards. Waage chose Chocolate Doom 2.3, a popular open-source version of Doom, for its compatibility with the Ubuntu 18.04 Long Term Support (LTS) distro, which was already running on OPS-SAT. Besides, Waage noted, 'We picked Chocolate Doom 2.3 because of the libraries available for 18.04 -- that was the last one that would actually build.

Updating software in orbit is extremely difficult, so relatively little code would have to be uploaded. As Waage said, 'Doom is relatively straightforward C with a few external dependencies.' In other words, it's easy to port. The only sign that Doom was running in space at first was a lone log entry. So, the team used the satellite's camera to snap real-time images of the Earth, then swapped Doom's Mars skybox for actual satellite photos. 'The idea was to take a screenshot from the satellite and use that as the sky, all rendered in software using the game's restricted 256-color palette,' explained Waage. Even this posed unexpected difficulties: 'Trying to draw all of these beautiful colors with those colors,' said Waage, 'it's probably not going to work right off. But we tried gradient tests, NASA demo photos. It took quite a bit of tweaking.' Eventually, instead of a fantasy Mars as the sky background, they got a good-looking, real Earth in the game's sky. The game itself ran flawlessly. After all, Waage said, 'It ran beautifully. It's on Ubuntu.'

Read more of this story at Slashdot.