The spy is a piece that, when moved adjacent to an enemy piece or inside an enemy city, can recover the enemy piece's ID code. (For a description of ID codes, see NAMES.) The piece could then be marked, that is, given a name which would be included whenever that piece was spotted from that point onward.

The ID code would give clues about where the piece came from, how many pieces of that type are being manufactured, how many cities were located on the continent, what that city manufactures, etc. The information would be incomplete and possibly misleading, but that's how it should be. If the player using a spy scrupulously provides optional names every time a new code is recovered, future codes will begin to make more sense.

Thus if a certain enemy fighter has the ID "1421-02-015", the player can assign to continent 14 the name "Japan", city 1421 the name "Tokyo", and the fighter itself the name "Kamikaze Ken". If Ken turns out to be an ace, other fighters will be warned whenever they move adjacent to him. And the next time the spy recovers an ID code, the computer will automatically substitute previously labeled code-portions, so that the next fighter spotted will have the ID "Japan 19-02-003" or "Tokyo fighter 21".

The spy itself could come in land, sea, or air varieties, although a spy-plane would probably be the most common. A spy piece would appear to the enemy as an ordinary fighter/destroyer/army, put would have a special type code in the second part of it's ID number, so that a spy could be uncovered by an enemy spy (whenever two spies move adjacent to each other, each recognizes the other and reports back; it takes one to know one).