Deal or No Deal is based on the TV game show of the same name. It puts one contest against a banker. At the start of the game, the player choose one of the 26 briefcases. They contain prize money ranging from $.01 to $1,000,000. The different amounts are shown on a game board. Each round the player has to open a number of the remaining briefcases which are then marked on the board (six in the first round, five in the second, four in the third). Based on the remaining amount of money, the banker offers the player a deal, a certain amount of money, based on odds. The player can choose to accept the deal when large sums are gone, or decide to go through. After the third round the briefcase is opened and if it contains a higher sum than what the banker offered, the player has made a great deal.
In singleplayer, three modes are available: TV Game (classic gameplay), Vault Game (Find the 3-number combination to a vault in the correct order in as few turns as possible. The initial prize is $500,000 and each turn the prize fund is reduced.) and High Low (Pick a briefcase and then make a calculated guess if the next briefcase will contain a higher or lower sum. For each correct guess, the prize money is increased). Two-player multiplayer offers Head to Head (classic gameplay to get the best deal) or Best Deal where one of the players becomes the banker.
Gameplay consists solely of picking numbers and calculated guesses. No other interactive game elements are present.