Blizzard IP started off from failing to acquire a license with Games Workshop, and did infringement-avoiding changes to release their own games. StarCraft is a

Blizzard IP started off from failing to acquire a license with Games Workshop, and did infringement-avoiding changes to release their own games. StarCraft is a subset of Warhammer 40k, which is an expansion of influences from Starship Troopers. Edit: The IP story seems unsubstantiated (albeit likely), but regardless the similarities between terrans/empire, zerg/tyranid, protoss/tau, etc are certainly there.