Running macOS 10.14 (Mojave) & 2.0.3 Doomsday Engine
When I attempt to add the Doomsday shell to "Accessibility" under the "Security & Privacy" panel in Settings (to prevent it from recognizing game input as macOS shortcuts), I cannot do so. Dragging and dropping the app doesn't add it to the list of excepted apps and I cannot hit the "+" button and add Doomsday. As a result, I can't play anything using default keymappings, because macOS will switch to things like the app switcher, desktop switcher, etc.
I've created a video
to demonstrate exactly what's going on