One of the extra features of Metal Gear Solid on the PlayStation was the VR (Virtual Reality) training which Snake could do to improve his sneaking and basic weapon skills. It basically involved sneaking around the same ten levels four times, each with different aims. It was an interesting extra feature of MGS (something that was left out of the Twin Snakes when MGS was remade for the Gamecube) but it had its attractions so a bonus add-on disc was released with about 300 levels to work through (the PC version of MGS came with it).
In Europe it was released as "Special Missions" and the United States released the same game under the title of "VR Missions". Here they are respectively:
Since Special Missions is only an add-on disc, it requires MGS to play. So because a disc of MGS has to be put into the console when prompted, Special Missions doesn't work on Sony consoles where the disc slides in (i.e. PlayStation 2 or 3) but does work on the original PlayStation, PSone or PS2 Slimline where the lid pops up.
With Special Missions, you can do all that you can do in the VR Trainng levels of MGS but more. The only weapon you could practise with in MGS was the SOCOM pistol but in Special Missions you can practise your weapons skills with all your weapons (C4, Grenades, Stingers, PSG1, Claymores etc.)
There are extra bonuses too, and a particularly popular one has been that you can play as the Ninja (which is suggested on the box cover). You can use his stealth camo, his ability to jump from place to place, his katana sword and his electric shield. Other interesting missions include solving Genome Soldier murder mysteries, which include working out who broke a surveillance camera, following footprints, searching a room for clues and even wearing a wig!
Some of the missions require a lot of skill or thought and the difficulty increases progressively as you advance through the game. Other missions are clearly just the results of the Konami team having a laugh, for example taking out two Genome Soldiers the size of Metal Gear before they stamp on Meryl, or shooting down a UFO before you are beamed up by it!
While it does get harder, you also gain more privileges as you advance through the game. You can watch special trailers and get opportunities to photograph Naomi Hunter and Mei Ling (I'm not quite sure why though...)
It has to be said that this is only a bonus add-on so don't expect it to have the same playability of MGS but still, it's a bit of fun when you want to sneak around (or not!) without having to face a plotline, but rather just dive in and out of whatever missions take your fancy!