Metal Gear Solid 2: Substance is the expanded re-release of Sons of Liberty. Featuring a whole host of VR Missions, alternative missions and Snake Tales, the game set out to correct the initial backlash regarding the change in main character role for Sons of Liberty. With a whole new list dog tags implemented into Sons of Liberty, which was included as part of the Substance disc, the game added replay value to a game many had already completed many times. The Xbox version of the game lacked the skateboarding mode and did not come with the The Document of Metal Gear Solid 2.