War Pigs is a hidded locked track on GH2 along with others. To get hidden tracks you have to play on career mode on medium setting or higher, complete the number of tracks to gain an encore performance to unlock hidden songs. Best one is at the later harder levels in England's Stone Henge and you unlock the full version of Freebird and an experience with an UFO.

As for getting the origianl recording, Black Sabbath does have the Black Box Set, but it's also release as a Classic Budget CD an essential purchase for any metal head of any age.