Pro-Pack, more commonly known as RNC, is a file compression utility used by several commercial games. It was developed by Rob Northen, who also produced the wikipedia:Rob Northen copylock copy protection scheme.
The compression utility was made available for the Amiga and IBM PC. It can compress Amiga Hunk, MS-DOS EXE, Atari ST TOS and Atari Lynx executables, as well as raw data files. Decompression routines written in assembly language were provided for 680x0 processors (Amiga, Atari ST, Megadrive), 80x86 (IBM PC), 65c816 (SNES) and 65C02 (Atari Lynx)
ProPacked data files begin with ASCII "
RNC", followed by an 0x01 or 0x02 byte to indicate the compression method used.