This is the most common origin. Older forum posts from Unknown Worlds refer to "ns.rar" as a distribution package for Linux server installs or specific beta patches.
The .rar extension indicates a compressed archive created with WinRAR. The "NS" prefix typically refers to one of three things in the gaming world: NS.rar
How do I add the personnel files expansion to the game? - Facebook This is the most common origin
Some users share compilation packs of fan-made expansions (like those for the game BLOOD ) under names like BLOOD expansions.rar or simply shortened "NS" variants. How to Safely Open "NS.rar" particularly for AlliedModders
In some modding circles, particularly for AlliedModders , the file contains custom HUD "Drawing" plugins or icons (like icons.amxx ) used in server-side modifications.