I'm only running Catalina because I am myself a developer.
Backblaze pops up an error message every once in a while because of changes Catalina makes to filesystem layout. And running a developer-only beta of a new OS always leads to stuff being broken. It is very, very far from irretrievably broken. I cut the video just after loading the overlay because I didn't want to show my online friends in the video. Originally posted by Jonathan McEvoy: Here is a video of me launching a game on Steam on macOS 10.15 Catalina.