The Cold War may be officially over, but some countries are still politically highly unstable and present a threat to life, liberty, the pursuit of happiness and any hopes of decent weather. One of these is Ruritania, a large and powerful Balkan country whose government is second to none in nastiness: for example, they had VAT, the Poll Tax and Terry Wogan long before everyone else.

Yes, make no mistake. These are the Baddies. And you are on the side of peace, prosperity, virtue, er, daffodils, er, well you know, all the nice things in life. In other words you're nauseatingly good and wonderful (just like in Real Life, of course).

So on with the story of the rarest BBC and Electron game of them all, Spy Snatcher, on which I worked closely with its author in 1991: There's trouble at MI7, that security agency so secret that they took down the big sign outside their office in Philby Lane, which said "Top Secret Place. Spies Only" and subsequently pretended to be The Megaboring Insurance Company. Not that any of this matters because in fact the Ruritanians know about it all anyway.

You're summoned to MI7 headquarters, popularly known as 'The Zoo' in order to unmask a mole. The chief of MI7, Sir Arthur Cayley, known to his friends (and even his wife) as 'Z', is extremely worried. Overnight, something has gone on with the safe holding the top secret plans for the new Sonic Macrothrodule. The suspicion is a leak on the inside and with Cayley is Superintendent Hardy of Special Branch.

"Our traditional morning trip to the 'Cloak and Dagger' pub has been delayed for an hour already," says Z. "And quite frankly we'd rather get p*ssed than conduct an investigation so if you can do it all for us we'd be very grateful. Thanks for arriving under a blanket and hiding under this table. After we leave, make sure no-one sees you either and perhaps plod around the safe looking for answers. We won't entrust you with our official suspicions 'cause you're far too lowly to understand them."

With that, you become MI7's only hope of catching the mole. What lies ahead is a challenge in the best traditions of espionage, involving reading secret files containing much bizarre information on possible moles, eavesdropping on suspects, hacking into the Zoo's MULTIPOCS computer, cracking codes and secret writings, disguising yourself with wigs, false beards and false noses, picking up and interpreting clues, understanding CODEHAK microfilms and even breaking into the laboratory of the mysterious Dr Ramanujan - maybe some of his secret technological breakthroughs can be used to help you in your mission? Or maybe the cleaner has something that helps against moles? (But who exactly is the Purple Yeti?)

At the end comes the inevitable showdown. You must catch the mole red-handed, and stop him or her from handing over the plans of the Sonic Macrothrodule to those sinister Ruritanians. If you fail then it's goodbye to freedom, daffodils, etc. and a new Dark Age will dawn. If you succeed, well, we'll all be very grateful and you'll probably end up with something in the New Year Honours list, plus a Licence to Maim, maybe even a Licence to Kill! So, get onto Topologika and get spy-catching while there's still time...