Perhaps I have been taken in. After all, isn't the CIA all about fooling the other guy and stealing his secrets so that you are one up on him? Not according to Mr Colby. "The function of intelligence used to be to gain advantage over the opposition," he says. "But in the past 20 years it has changed. Now the main job is to establish factual information, to understand what is going on."
The reason I was having lunch with the man who was in charge of the CIA for most of the Nixon years and in charge of the CIA's operations in Vietnam for considerably longer was that at the age of 75, Mr Colby has decided to get into computer games. Working as a director and consultant on Spycraft: The Great Game, he has found a new outlet for his vision of the misunderstood world of the intelligence community.
"I have written books and articles and been asked to help out with TV shows. But I don't think TV can give a real feel for what the work is like. It can't explain the importance or the real need for it. I think you can do that quite well in a computer game," he says. The traditional computer game world of spies as heroes, lurking in dark doorways ready to kill members of the opposition, is not what Spycraft is about.
The real world of intelligence is mostly an intellectual pursuit, says Mr Colby; there is "a lot of reference work and a lot of background". But he adds, with a twinkle in his eye, that sometimes you require a "little bit of derring-do".
The challenges for the modern spy, he maintains, are tricky ethical problems, crisis management, dealing with the overwhelming weight of factual information and so on. That is the reality Activision is trying to bring to a computer near you. Spycraft, written by James Adams, the Sunday Times Washington bureau chief and writer of spy novels, has cost about $2.5m to make. Although a final version is not yet available, the almost finished version boasts some excellent films to introduce the various scenes and some clever and varied game playing.
The game includes an online element. By connecting to the World Wide Web, it pulls down up-to-the-minute headlines and builds them into the story. Extra parts of the game, such as a complex encrypted message interchange, can take place on the Web, where you will be competing with other spies or intelligence operatives to crack codes. In the game, the user plays a spy called Thorn, who must help to prevent the assassination of the president of Russia. Thorn has to make professional decisions, perform well in crisis management, co-operate with the Russians and deal with the new types of bad guys, who include terrorists, drug barons and the like.
A torture scene has caused Activision problems with the British Board of Film Control and may well be cut out of the UK version. This is ironic as Mr Colby is vehemently opposed to torture - not on ethical grounds, but because information extracted under torture is notoriously unreliable. Activision says the purpose of the torture scene is to force Thorn into deciding what to do. It is one of the starkest moral dilemmas of the game, but it is also one of the most violent scenes. The censuring process means the game is unlikely to appear in Britain much before the end of February.
Mr Colby, however, is still so enamoured of his experience with CD-Rom games that he has let himself be persuaded to take part in online conversation sessions with users. He will give tips and answer questions. Of the mysteries of CD-Rom, he says: "Fascinating. It is a whole new world I know nothing about."
Spycraft will be available towards the end of the month, price pounds 40-pounds 50.