There is a story about a man receiving a visit from the Special Branch (for non-Brits - this is the nearest thing we have to secret police - a police section dealing with spying, subversion and extremism) after a communication to him from abroad was intercepted. It said, "The Russian bear is preparing to infiltrate Liverpool". Presumably the man showed the officers his Diplomacy board, pointed out the supply centre of Liverpool and demonstrated how a Russian fleet might reach it.
Maybe that story is apocryphal, but I've been chatting on a train and noticed people beginning to listen in as I said something like, "If France and Germany make common cause, England can be smashed. The Russians have enough on their plate already because of the situations around Romania and Warsaw, so the only possible fly in the ointment is Italy."
Welcome to Diplomacy, a game based on Europe at the start of the 20th century and the rivalry of seven great powers. It's a board-based war-game. Immediate qualifications: you can play it on-line, though I'm not aware of genuinely interactive versions; and it's a war-game much in the way chess is. In fact you could describe it as seven-sided chess, with two important characteristics - the moves by all the players are made simultaneously (so you have to try to predict what others will do) and diplomacy between players is allowed, indeed encouraged. So you talk to neighbouring powers, try to get a sense of what they're planning, make offers for mutual support against third parties and, occasionally, make threats. In some versions of the game this is done face-to-face and with limited secrecy, while diplomacy conducted at a distance by phone is genuinely secret. However, no promise made is binding. You can promise one thing and do the opposite. If you do this too often, though, no-one will believe you and you will find yourself without allies. As there are seven powers in the game at the start, anyone who tries to go it alone in the early stages usually gets eliminated.
There are aspects of the game that have made me pause at times. You are expected to lie: but the game is based on a community of people agreeing to lie, just as a football or cricket or chess game requires players at time to deceive, albeit without words; and like other competitive games, a well-fought contest generates deep respect for the opponent.
I won't go into the technicalities here, but the technical side of the game is fairly simple and the skill lies largely in reading other people's intentions, in building up relationships and in timing decisive moves right. One player wins when he or she controls a majority of the "supply centres" on the board, but agreed draws are possible, mostly when a stalemate line has been reached.
I was introduced to a diplomacy circle many years ago by Martin Proctor and am still in it. Currently, as the President of France, I have indeed infiltrated Liverpool and, with the Germans, eliminated England, but a little difficulty has just developed with Italy, who may quite possibly read this post, so of course, it's all a storm in the Western Mediterranean and we're good friends really...