The Behind Closed Doors Demo works on macOS systems with both Apple Silicon (M1/M2/M3) and Intel processors.
I'm also aware that Steam has recently been displaying the notice:
“Notice: This product is not compatible with macOS 10.15 Catalina or above.”
on some products even when they do work correctly on Catalina and newer macOS versions. This appears to be a Steam-side display issue.
To clarify: the Behind Closed Doors Demo runs normally on macOS Catalina and above, and macOS users should be able to download, install, and play the demo without issues.
If you’re playing on macOS, feel free to share your experience, feedback is always welcome.
Best wishes,
Ennushka