Normal Dark Souls worked fine, but some options in the essential DSFix mod cause the game to crash. I consider the mod mandatory so I'm leaving this as a tweaked report even though the vanilla game installs and runs on its own. Must have aaQuality 0 and ssaoStrength 0 or the game won't start. I turned on anti-aliasing override in my graphics card control panel to improve the visuals.

The OBS_VKCAPTURE line is to enable game capture in OBS for this title. (This is a tweak to OBS.)

The Vulkan shaders are noticeably darker than on Windows.