During the Stadia conference at GDC last year, Marty Stratton of id Software said that Doom Eternal would be an ideal game for showcasing the capabilities of the game-streaming platform. "If you're going to prove to the world that you can stream games from the cloud, what better proof that Doom?" he asked the audience, before stating that Doom Eternal "will be capable of running at true 4K resolution with HDR color at an unrelenting 60 frames per second."
That drew applause from the crowd, but it turns out to be not quite accurate. The Doom Eternal launch details page released yesterday, which provided the PC system requirements and unlock times, also notes—down amidst the console information—that "Doom Eternal on Stadia will run at 1080p @60 FPS on HD displays and up-sample to 2160p from 1800p @60 FPS on 4K displays." In other words, not true 4K.
1800p isn't a especially common resolution, although some developers opt for it as a compromise between image quality and performance on consoles: Tripwire Interactive Told Wccftech a few years ago that Killing Floor 2 runs at 1800p on Xbox One X because the frame rate drop at 4K "was a bit too significant," for instance. And it is a big step up from 1080p—but it's not "true 4K."
It's another knock against Stadia, although VentureBeat has an interesting rundown of why it might not be fair to pin the blame on it. The short version is that Doom Eternal is an extremely demanding game: The 4K/60 fps "Ultra-Nightmare" setting requires an Intel Core i9-9900K CPU, an 11GB RTX-2080 GPU, and 16GB RAM. Reducing the graphics options will presumably dial that back somewhat, but there's no escaping the need for serious hardware if you want to run at that resolution. (The Doom Eternal system requirements page doesn't say what graphical settings the Stadia version will run with.)
The 4K situation on Stadia has always been a little hazy. As we noted in a 2019 report, Stadia streams at 4K and 60 fps, but individual games may not run at that resolution: Both Destiny 2 and Red Dead Redemption 2, for example, are upscaled from lower resolutions. But Doom Eternal was presented very specifically last year as a showcase for Stadia's 4K capabilities—something that it now appears incapable of doing.
I've reached out to Bethesda for more information and will update if I receive a reply.