libmpq is a library which can be easily used in own applications
and a set of tools for manipulating mpq archives.

MPQ, or MoPaQ, is a proprietary archive format created by
Mike O'Brien, the man hailed as Blizzard's multiplayer engine
genius, back in 1996 as a general purpose archive for use with
Diablo, and named narcissistically for its creator
"Mike O'brien PaCK". The copyrights to it, however, are held by
Havas Interactive, Blizzard's parent company. The archive format
is used by many Blizzard titles like Diablo, Diablo 2, Starcraft,
Warcraft 2: BNE or a newer version in Warcraft 3.