A mad scientist has created mutant, fire-breathing ducks that lay radioactive plutonium eggs. The player must collect the eggs to prevent the scientist from using them to build a doomsday device, while avoiding the ducks and other obstacles.
The player uses the joystick to control a robot that explores the scientist's lair, picking up eggs, weapons, and other useful objects. When two eggs are found and brought to the appropriate exit, the player advances to the next level.
The player starts with three lives (robots) and loses a life when eaten by a duck or hit by the ducks' fire or another deadly object. Additional lives and various power-ups can be earned by picking up colored balloons. The player can choose to play with all objects either in a predetermined location, or randomly distributed throughout the rooms in the game.
Duck Attack! was originally conceived as a ROM hack of the Atari 2600 game Adventure, but was then rewritten as an original title. Like most Atari 2600 games, Duck Attack! uses 128 bytes of RAM to hold all game variables and program call stack. The game uses an unusual 3-line kernel technique to produce sprites that are larger and more detailed than those usually seen in Atari 2600 games.