Ace Combat 04: Shattered Skies is a game for the PlayStation 2 made by Namco. It is a semi-realistic fighter pilot simulation.

The player takes on the role of the top fighter pilot, Mobius 1, of the Mobius Squadron in the Independent States Allied Forces (ISAF), fighting against the Erusians who have occupied almost all of the Usea continent.

Between the missions the story is told through letters written to Mobius 1, from a boy whose parents were killed when a fighter jet crashed into their house. The fighter jet was shot down by Yellow 13, the Erusians top fighter pilot, and a member of their Yellow Squadron (the Erusian equivalent of the ISAF Mobius Squadron). As he is forced to move into an occupied town, he befriends Yellow 13.

During the course of the game, the player has the opportunity to buy approximately 20 different planes, from those that actually exist to prototypes, and their weaponry. Every plane has two alternate looks, gained by achieving a superior, or S, ranking on a stage in hard difficulty mode, by shooting down the ace pilots which are on each stage, or by completing the challenge modes.

This game is the fourth in the series of Ace Combat games, the first three being Air Combat, Ace Combat 2, and Ace Combat 3. The reason this game is called Ace Combat 04 is because the 04 in the title stands for the date in which the game mostly takes place in the year 2004. The next title in the series, Ace Combat 5, returns to the old numbering scheme, as the game starts in the year 2010.