In Gangs of London the player takes the role of a crime gang member who wants to take control over London. The basic gameplay premise reminds of the GTA series but instead of a free roaming experience the campaign consists of 70 short missions which are chosen through a menu screen. Every of them is accompanied with a story sequence in a comic style and features varied goals: escorting, infiltrating an enemy post, stealing cars, kidnapping people, racing, defending the own position against enemy waves and killing people.

The gameplay itself offers what one would expect from a game like this: if the player is on foot the game is basically a third person shooter - sometimes he has a few other gang members with him and can give them a few commands. The driving is action oriented in either first or third person and the stealth segments are basic and require only to perceive the guard's patrols and kill them from behind. The police intervenes if they see a crime but there is no wanted system like in similar games. At the beginning of the campaign the player has a choice between five gangs with different abilities, e.g. the Triads can drive faster.

Additionally the game features a big selection of playing modes and mini games, e.g. free roaming in London, driving taxi, photographing points of interests as tourist or fighting off zombies. The mini games in the pub can be played with two players: darts, bowling, pool and a Snake variant as arcade machine, The last noteworthy mode is a tactical game similar to Risk: The player takes control over a crime organization and tries to conquer London which is divided into about 30 districts. In every round he can perform three actions, e.g. move men to another district. Between rounds he can hire more men or acquire bonus cards which give certain advantages. There are three difficulty levels and several winning conditions for this mode.