The Fourth Protocol is an interactive fiction video game based on Frederick Forsyth's 1984 spy novel The Fourth Protocol. The game was released in 1985 by Hutchinson Computer Publishing, a subsidiary of the publishing house Hutchinson. It was designed by John Lambshead and Gordon Paterson, and programmed by Ben Notarianni, Rupert Bowater and Paul Norris of the Electronic Pencil Company. The game was released for the ZX Spectrum in July 1985, with the Commodore 64 release following one month later, and the Amstrad CPC conversion in 1986. The game is split into three parts, and large sections of the programming were outsourced to others: Andrew Glaister (program conversion Spectrum, parts one and two), Dave Jones (programming Spectrum, part three), Ray Owen (graphics Spectrum, part three) and John Gibbons (programming C64, part three). The IBM PC version was developed for the Electronic Pencil company, by a developer named Brian Mallett. The PC version was written in 8086 assembler and used CGA graphics in 4 colour mode. The PC version was ported from the Z80 and 6502 versions. The PC version did not use DOS but booted up from its own floppy disk. The game was published in the US by Bantam Software. Gameplay The game comprises three sections: "The NATO Documents", "The Bomb" and "The SAS Assault". In order to progress to the last two sections, the player must solve riddles based on the current and any previous sections. Macintosh-like icons are used to assign watchers and navigate until text-based interaction becomes available in the third section. The NATO documents The scene is Preston's office. The player takes the role of John Preston, the new head of Section C1(A). Somewhere in England, a burglar steals the famous Glen Diamonds, but he also finds some secret NATO documents. He alerts the MoD by sending them the documents anonymously. The Paragon Committee decides that John Preston's most important task is to find out who is leaking secrets, to whom they are being leaked and why. Other events occur along the way which also demand his attention. The Cencom icon offers access to Preston's personal files where the player can store information throughout the first part of the game. The Assessment icon gives the player an idea of their progress, telling the player how much of the first stage they have solved and their current rating at MI5. Using surveillance the player can assign