The phrase nt.rar doesn't point to a single, well-known story or franchise. Depending on where you saw it, it could refer to a few different things:
: A fictional universe or "ARG" (Alternate Reality Game) often shared via compressed files like .rar on forums or Discord.
: Sometimes "NT" is used as shorthand for "Night Terror" or specific fan-made expansion scripts for the Metal Gear series.
: A common sci-fi trope where a file titled nt.rar contains forbidden blueprints or AI code.