On October 1, 2004, Konami released a mobile phone version of Metal Gear 2 in Japan for the i-Mode, EZweb and Vodafone services. This was the first time the game was ported to another platform since its original MSX2 release in 1990. Several changes were made in order to modernize the game:
New game modes and items - All the new game modes (Easy Mode, Boss Survival) and items (Infinite Bandana) introduced in the mobile phone version of the original Metal Gear were included in this version as well.
Revamped character designs - The character face shots shown during the game's radio mode (as well as the opening intro) were redrawn by Metal Gear Solid character designer Yoji Shinkawa. While the original designs in the MSX2 version resembled actual movie actors and people, the designs in the new version are brought more in line with Shinkawa's designs from the Metal Gear series.
Rewritten script - The script was changed to include more kanji characters than the MSX2 version.
Name changes - Like the mobile phone version of Metal Gear, some characters' names were changed:
Natasha Markova was changed to Gustava Heffner.
Yozef Norden was changed to Johan Jacobsen.
Petrovich Madnar was given the full name of Drago Pettrovich Madnar, establishing the name "Pettrovich" as the character's patronymic middle name.
Black Color was changed to Black Ninja.
Ultra Box was changed to the Four Horsemen.
Night Sight was changed to Night Fright.
Modified items - Some of the items were modified (graphically and functionality) to parallel their usage in the Metal Gear Solid games.
The graphical icons for each of the three ration types are now colored differently to tell them apart.
Equipping the cigarettes will now drain the player's life bar. Moreover, the graphical icon was changed to no longer resemble a package of Lucky Strikes.
Thermal goggles are now available to see through infrared sensors as an alternative to cigarettes.
In the MSX2 version, the player could only place six landmines per screen. In the mobile phone version, this was increased to sixteen.
The time it takes for Gustava's brooch to change shape was shortened slightly.
The time for an egg to hatch was shortened as well.
Modified play mechanics - Certain aspects of the gameplay were changed to make the game easier for the player.
The tap codes were changed.
A mark will appear on the player's feet when making a noise while walking on certain types of terrain.
If a hollow wall is punched, a question mark will appear over it.
Frequency numbers are now saved under a memory window after dialing them the first time.
Campbell's second frequency (which originally could only be learned by checking the rear side of the MSX2 version's packaging) is now given to the player instead.
