In the context of the Nintendo Switch, (Nintendo Submission Package) is the official file format used by Nintendo to bundle and distribute digital games, updates, and DLC through the eShop.
Another angle is that “black top” could be a colloquial name for a specific scene release group that packaged the NSP file. Many pirated Switch games are distributed by release groups (e.g., "SUXXORS," "Venom"). While no prominent group named "Black Top" is currently active in the Switch scene, it is plausible that the term refers to a smaller, non-English distribution. assassinscreedtherebelcollectionnspblack top