Gangs of London follows the story of a crime gang member who seeks to dominate London. The gameplay revolves around completing 70 short missions, each with its unique objectives such as escorting, infiltrating enemy posts, stealing cars, and killing people. These missions are accompanied by comic-style story sequences that provide context for the player's actions.
The game features a diverse range of playing modes and mini-games, including free-roaming exploration of London, taxi driving, photo-taking as a tourist, and zombie-killing. Multiplayer options include pub games like darts, bowling, pool, and a Snake variant. The tactical mode is similar to Risk, where the player must conquer London by dividing it into districts and making strategic decisions.