Metal Gear Solid 2: Substance is an enhanced port of Metal Gear Solid 2: Sons of Liberty, first released for Xbox before being ported to PlayStation 2 and Microsoft Windows.

Substance contains the main Metal Gear Solid 2 game along with some subtle changes, including new infrared effects for the thermal goggles, additional cut scenes, and a new set of nameplates.

The subtitle Substance was inspired by Hideo Kojima's love for the bands Joy Division and New Order, both of which shared members and released albums titled Substance.



Characteristics:

- Substance's main addition is the inclusion of nearly 500 standalone missions (similar to VR Missions/Special Missions).
- In Missions mode, the player can choose between Solid Snake and Raiden, as well as five alternate versions of the two (such as Raiden in the Cyborg Ninja exoskeleton or Snake in his original stealth suit from Metal Gear Solid).
- Substance also includes five plot-driven Snake Tales missions starring Solid Snake.
- Due to the low production value of these missions, there is no spoken dialogue (plots are narrated via on-screen text at key points) and all enemies and areas are from the main game (most taking place in the Big Shell).



- Many changes have been added to the main game. Substance's intro now has a typewriter sound when a name appears in the main intro.
- This sound is not heard in Sons of Liberty. A new series of nameplates has been introduced to the game and the player has the option to choose between the 2001 series and the 2002 series nameplates after beating the game.
- Some marines now have nameplates to collect when the player is in the hold (this is only available for 2002 series nameplates).
- The player can find a silencer for Snake's USP in the second playthrough. New posters can be seen throughout the game. Nikita has been moved to a new location.
- In the Plant chapter, the number of bombs the player must defuse to enter the hold depends on the difficulty setting.