Deal or No Deal: The Banker is Back is the second Nintendo DS game based on the UK version of the game show Deal or No Deal. The main difference from the first game is that it replaces the original 2D sprites with 3D models. Like in the TV show, the player has to choose one of 22 boxes, each which contains a cash value between 1p and £250,000. The player then starts opening boxes to reveal the content of each. Between rounds, the player is given an offer from a banker and can choose either to keep playing or to take the money from the banker.
The game contains three single-player modes. There is the classic mode which plays like the TV show, the banker mode where the player gives offers to an AI-controlled contestant and the banker's bonus mode which is like the classic mode but where the player can challenge the banker. This is done by playing a game of Mastermind after rejecting the banker's offer. Another challenge involves rating the banker's offer by choosing from a list of words (ridiculous, greedy, fair, generous or terrific). If the player completes a challenge his respect level increases and as a result will get better offers from the banker.