Hideo Kojima is the director and producer of the game. He began to work on a sequel of Metal Gear 2: Solid Snake in 1994. The game (called Metal Gear 3) was going to be released for 3DO, as Kojima was still working on Policenauts, which came out for that system in 1995. Prior to its release, Konami issued Policenauts: Pilot Disk, which contained a playable demo of the game and other features. Among them there are two artworks by Metal Gear Solid’s illustrator Yoji Shinkawa, one depicting an early version of Snake and Meryl Silverburgh (also a Policenauts character), the other one showing presumably an early version of the FOXHOUND group, or different Metal Gear Solid characters. Images via Ashura on lostlevels.org forums.
The development naturally switched to the Playstation, with Kojima also working on the conversion of Policenauts and Snatcher. The game’s name was also changed to Metal Gear Solid, reflecting Kojima’s ideals for a new Metal Gear title (via Wikipedia):
Kojima: “Metal Gear” is as it is, and “Solid” has a deep meaning. Let me explain. This time Metal Gear is displayed in full polygonal form, and I used “Solid” to describe the cubic structure. also, the “Solid” means to the third power mathematically. Also, most of the people don’t know that there is a Metal Gear 1 and 2 for the MSX, and I wanted it to be the sequel for those. And, of course, Solid from Solid Snake
The game was first shown at the Tokyo Game Show 1996, and previewed in various magazines.
This version shown in this video is probably a non-playable tech demo, not even running on a Playstation hardware. The game engine is completely different from the final game, along with other differences. Decoy Octopus is missing from FOXHOUND members, and Vulcan Raven is spelt “Valcan Raven” (it may be some sort of Engrish). Snake seems to be around a very early version of B2 level Armory in the Tank Hangar. The interfaces of the inventory, HUD and CODEC are completely different; the radar is quite different too, especially in Danger situation (there is also a Caution alert when an enemy is near Snake). Early versions of the Ninja and Revolver Ocelot also make appearances, as well as the Metal Gear Rex. The trailer showcases all the features of the game (“Sneaking In”, “Armed”, “Encounter” etc.) but I find really strange that “Escape” is associated with a picture of the Hind-D helicopter (one the bosses). You can see various screengrabs and magazine scans in this gallery (some magazine scans from DarkMirage, on X-Cult Forum):
Images, 1996 version:
Another possible build is the one shown in these screenshots, featuring a very early Tank Hangar, a different Heliport (with a forklift) and an unknown test room with soldiers (it could be a much earlier version of the Tank Hangar, since the shape of the passageway is similar). All screens are from IGN.com (thanks to looser for the link).
Early Tank Hangar and unknown test room:
Then we have many different trailers, all dating back from 1997, shown at the E3 and Tokyo Game Show. They all look from the same build (some of them even show the same scenes), and the most famous of the group, the one in which Snake blow up everything with the C4, was featured in many Playstation’s demo discs in various magazines. They share many differences from the final version: the camera appears to be more controllable, vision cones are different in colour, the lifebar is in the middle of the screen, not in the upper left corner, the radar is simpler in its Danger and Caution status, and it’s active during boss fights, Snake carries a lot of ammunitions and he can move while he’s crouched. Let’s analyze everyone of them:
Notable differences: the Heliport is similar to the final version, although the forklift is still present (and it’s moving too! at 1:45 you can see another view of the moving forklift), first person view does not feature the green vision cone in the radar (also the Surveillance Camera is without vision cone), Tank Hangar has got the wrong type of guards (I’m not very sure about this), Snake has a flying kick move (in the final version he can kick, but not with a jump), Snake remove the pin of grenades with his teeth. If you know what Hideo Kojima is saying please drop a comment in the comments section!
Notable differences: now Snake has the first person vision cone, items have different names ( final->beta: Scope->Finder, Cigs->Moslem,), Snake fights the Ninja in the corridor (not only in Otacon’s lab), Snake use the Scope in Meryl’s prison (it’s impossible to go there while Meryl is still in prison), you can see Meryl and Snake shooting in Psycho Mantis’ room (without the boss, no action take place here, the radar also goes in Danger mode).
Notable differences: lots of unknown items (or early version of the final objects), it’s difficult to see the names and the icons. There are BD DISK (early version of Kenneth Baker’s disk?), WOLFS, HUIDADRG, MG GK2 and STEPS. The Scope does not feature a vision cone, the crane is missing from the Blast Furnace, the radar is active in the Underground Passage to the Communications Towers (it should be in Jamming mode), Night Goggles are named RNPAS-7, the door of the Nuclear Storage building is completely open, the elevator door of the Tank Hangar is different, and finally, Snake is fighting with Meryl at the top of the Communication Tower (in the final game Meryl is shot in the Underground Passage by Sniper Wolf, although this scene may not represent a plot change, rather a scene created only for the trailer).
There have been rumours about a Nintendo 64 and Saturn version of Metal Gear Solid. The Nintendo 64 version is mentioned in this article by Gamespot, but I couldn’t find any reference on the web about a Saturn version:
Konami insiders have informed GS News that Konami’s modern platform update to the popular NES series Metal Gear will be coming to the Nintendo 64 console system, though originally planned solely for the PlayStation.
HackOut Games has got a nice collection of hacking videos of Metal Gear Solid’s Pilot Disc on his YouTube channel: you can see a collection of unused animations, unused music and unused camera angles.
Also, John Doom found some differences between the final version of MGS and its Pilot Disc (SLPM-86098): check the video below to see them.