Some of them were inserted with permission, like the tracks on Rock n' Roll Racing, the digitally patched-together Guns n' Roses and The Who pinball tables, or the little-known Journey arcade game. Some were completely unauthorized, like some of the tracks in Rock 'n Rage, Cosmo's Cosmic Adventure, and Duke Nukem II. There's even a collection of Bobby Prince's original drafts for the Doom soundtrack, which are blatant and awesome metal and alternative ripoffs that were later changed up to avoid lawsuits.