The Crystal Maze is a British game show devised by Jacques Antoine, based upon his format for the French game show Fort Boyard, and produced for Channel 4. The programme focuses on teams of contestants, a mixed group of men and women, attempting a range of challenges to earn time required to help them complete one final challenge, which if completed successfully earns them a prize. The premise of the show is themed around challenges set to different periods of human history within a fictional labyrinth of time and space. It used golf ball-sized Swarovski glass crystals as a reward for each challenge successfully completed by contestants, and lock-in conditions for contestants that ran out of time or broke a three-strikes rule on a challenge.