Action Man: Robot Atak is based on the direct-to-DVD animated film of the same name, in turn based on the line of toys. To stop the evil Dr. X and his army of robots that have been attacking cities across the globe, Action Force seek out his secret hideout, Island X. Dropped on different parts of the island, Action Man, Redwolf and Flint must first find each other, and then put an end to the evil doctor's plans.

Most of the game's 17 levels take the form of a side-scrolling platformer with a heavy action focus. To get to the level exit, the controlled character must jump pits and gaps, climb ledges and take out many enemies, different varieties of X' robots and various animals native to the island: spiders, bats, even dinosaurs. Each character has slightly different abilities (until the finale, which hero is controlled depends on the level): Native American Redwolf always carries his bow, while Action Man and Flint start most levels with only their fists. They can pick up weapons, though, including throwing discs (for Action Man only), several different guns (which can be further enhanced by timed power-ups) and a boomerang (for Australian Flint only). Only Flint can double jump. Picking up 50 Action Man icons gives an extra life. Regular extra lives and health power-ups are also available, and a reset checkpoint is available every few screens.

Variety from the platform levels comes in two levels where Flint uses his dirt rider and Redwolf surfs the waves. These are seen from behind the heroes as they must avoid or blast away obstacles and collect Action Man icons. Action Man lives up to his name in a level where he rides a motorcycle up a volcano (shooting missiles at enemies and jumping across gaps) and another one where he straps helicopter blades to his back to fly towards the level end.

The world's leading toxins specialist, Professor Moran, is kidnapped by a villain named No-Face while in disguise as Action Man in order to frame him for the kidnapping. No-Face intends to force Moran to make him a mind control gas. Action Man and Action Force become wanted criminals and their base becomes surrounded by the authorities. No-Face takes Moran to Island X, where he reveals that he has constructed an army of 'X-Robots' which begin terrorizing cities across the world. No Face has also began rebuilding Dr. X and brings him back to life as he was previously defeated by Action Man. Action Force escape their base with some of their equipment and vehicles and go on the run whilst battling X-Robots along the way. In one instance, Action Man places a tracker on an X-tank and tracks the robot's location to Island X. Action Force make their way there and later find out about Dr. X and No Face's plan to turn the world's population into their slaves using Moran's mind control gas. After several confrontations and battles, the evil plan is thwarted and the base is destroyed thanks to Flynt redirecting the missiles containing the gas to their launch point. Action Force leave with Moran, though they do not realize that Dr. X and No-Face have survived the explosion.