Mortadelo y Filemón: Armafollón is a side-scrolling action platformer based on the Spanish comic series Mortadelo y Filemón, known as Mort & Phil in English. The game features all the characters from the comic, and the player can control either Mortadelo or Filemón depending on the level. Each character has different abilities. For instance, by using different disguises, Mortadelo can transform into different characters, like a rocker who smashes enemies with his guitar, a caveman with a club as weapon, a granny, a snake, a tank and more. Filemón in the other hand, can use different weapons, as a plunger gun, a heat gun, etc.
The levels are varied with indoor and outdoor locations. In some levels the characters have to use different vehicles, like a jet ski or a car. There is one level inside a sinking ship, where the water is rising and the player has to hurry up to stay above the water level to avoid drowning, while fighting enemies and avoiding obstacles at the same time. The water effect was very advanced considering the platform limitations, with simulated refraction and wave effects which deformed the part of the level under water.
The player advances from level to level defeating different bosses and advances through the story, which resembles the funny and bizarre situations from the comics.