Four contestants each stand at a podium inside a glass cube. Each of the podiums has a panel with 19 squares on it, each representing one of the show's 19 keys. During the first two rounds of play, the host asks a series of questions, correct answers would randomly eliminate one of the show's 19 keys on that contestant's panel, whereas incorrect answers would cause one key to be relit. In Round 2, the contestants have the option to answer a question for themselves or pass it to one of their opponents in the hope that they get it wrong. Upon reaching seven keys eliminated, the contestant could either relight one key each on two of their opponents' panels or two keys on one opponent's panel. However, in round 3, contestants are given a choice as to how difficult each question was, with three levels of difficulty. As the game progressed, two timers, a clock timer and money timer would run concurrently with one another. For the first 15 minutes of play, the Money Timer would start at zero and rise at a rate of £500 per minute until the maximum of £7,500 was reached, at which point it would start to rapidly dwindle until it reached zero. During the game, each player could press a red button on their podium and have 10 seconds to select a key, and if it is the wrong key, that player is eliminated and has to leave the set, but if it is the right key, the player would win all of the prize money.