I think the two things are different. "Boss mode" is a quick cover to hide something you're doing (e.g. hit F9 to replace a game screen with a black screen with

I think the two things are different. "Boss mode" is a quick cover to hide something you're doing (e.g. hit F9 to replace a game screen with a black screen with a command line), but this is a complete replacement UI for doing the actual activity while appearing to be working.