Improbable? Yes - but as any hoopy frood knows, improbability is The Hitchhiker's Guide to the Galaxy's stock and trade.Based on the trilogy in five parts, the late great Douglas Adams teamed up with Infocom (makers of Zork) in 1984 to create the wildly popular text adventure game called (not surprisingly) The Hitchhikers Guide to the Galaxy. It was witty, it was fun - it was everything the books were.And it's about to turn 30.To celebrate, BBC Radio 4 Extra (a comedy station in the UK) has announced that they'll be publishing a 30th anniversary edition of the Infocom classic. It sounds surprising, but when you realized BBC Radio 4 did the same for the 20th anniversary… maybe less so. And when you remember that Hitchhiker's started life as a BBC radio program in 1978, all the pieces seem to fall into place rather nicely.