BTSX is an abbreviation of "Back To Saturn X", which a series of map pack (or WADs) for the video game Doom 2, it's often praised for it's beautiful
architecture and visual for a map pack build in a 1994 game engine, but it's also sometimes criticised that the maps are so consistently well done that it felt
repetitive.
the phrase can be used to describe a game level or a series of things that's so consistently perfect, it's
repetitive and unintuitive.