It runs about as long as a film, two and a half hours in Falmouth, except you are in it and someone might betray you. In plain terms: a 2.5-hour team spy game on foot, played on your phones. No guide means no one to impress and no one to blame. Just your crew and 2.5 hours of increasingly bold decisions. You will decode messages, photograph evidence, and keep a straight face in public. No experience needed. There may or may not be a double agent on your team. About 2.5 hours, 4 stops and roughly 1.8 km on foot. There is no guide, so nobody will make you stand still and listen. The verdict: better than a film, mostly because nobody shushes you, and you leave with the photos. Who it's for: friends, couples and families with teens; and private groups, from bachelor and hen nights to work teams and active over-55s. Book a private game for 1 to 8 players on a date you choose; a team of one works too. Bigger groups play as several private teams.