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Capcom today announced the Windows PC version of Resident Evil 2 supports the 21:9 aspect ratio.
The ultra wide aspect ratio is enabled in the 1-Shot Demo that was released today. That's a great way to benchmark your performance.
Important notes: You may encounter bugs in the 1-Shot Demo if you use the "Max" graphics preset; and cutscenes might stutter if you have HDR Mode "On."
Image credit: Capcom.