Code Age (コード・エイジ, Kōdo Eiji) is a 2005 multimedia franchise developed and published by Square Enix. It was created by Yusuke Naora and split between three projects; the manga Code Age Archives, the mobile role-playing video game Code Age Brawls, and the PlayStation 2 action role-playing game Code Age Commanders. Code Age uses a science fiction setting on the inner surface of a hollow world similar to a Dyson sphere. The narratives revolve around an apocalyptic threat to civilization, with the protagonists gaining powers from absorbing monsters dubbed the Otellos.

The concept for Code Age was created in 2002, being adopted into Square Enix's "polymorphic content" strategy of producing series across multiple platforms and media. The development team behind the project went under the name "Warhead". Naora led production and created the story for the series, Toshiyuki Itahana designed the characters and directed Commanders, and Kumi Tanioka composed the music for Commanders and Brawls. The manga was created by Aya Kyu under Warhead's supervision, with Naora designing the characters.

The manga Archives was serialised Monthly Shōnen Gangan from 2005 to 2006. The console game Commanders was planned for a Western release, but this was cancelled after the translation had been completed. The mobile entry Brawls operated for less than a year before closing down in September 2006. Reception of Commanders and Brawls was generally positive from Western critics, though Commanders met with low sales in Japan. The Code Age project was also noted for its ambitious multimedia approach at the time.

Code Age is a multimedia franchise developed and published by Japanese company Square Enix. The franchise, created by artist Yusuke Naora, is divided between three projects; Code Age Archives, Code Age Brawls, and Code Age Commanders. While the three Code Age projects are different genres and media, all share the same science fiction-themed universe, taking place over a prolonged span of time. Each project was abbreviated using a lettering formula; "CAA" stood for Archives, "CAB" for Brawls, and "CAC" for Commanders.

The series takes place inside an "intraglobular world" (球内世界, kyuunai sekai), a fictional hollow world similar to a Dyson sphere, with people living on its internal surface; at the sphere's center is the Central Code, a structure which resets the world every ten thousand years by wiping out the current civilization in an event called the Reborn. In an attempt to survive the next Reborn, its residents construct Arks around the Central Code. The plan fails as the Arks are struck out of orbit, and the population is attacked by Otellos, a species that mutates people into mindless Coded. Ark survivors can absorb Coded, transforming into powerful warriors dubbed Warheads. Survivors splinter into factions, some fighting each other and others hiding underground. The narrative of each property is standalone, but also ties into the storylines of the other Code Age projects. Recurring characters across the different media include Gene, a protagonist from Commanders; and R, who appears in Brawls and acts as a central antagonist in Archives.

Code Age Archive: Saigo ni Ochite Kita Shōjo is a manga that follows Thayne and Nico, high school friends who survive the collapse of the Arks and are forced to survive the ruined world. It began serialization in Square Enix's Monthly Shōnen Gangan magazine on February 12, 2005, with the first issue incorporating full color panels. The final issue was published on February 10, 2006. A prequel chapter was released as a pre-order bonus for Commanders bundled with the first issue in color. The manga was released in three volumes by Square Enix on July 22 and October 12, 2005, and March 22, 2006.

Code Age Brawls: Futatsu no Kodō is a role-playing video game released for mobile phones. It released five episodes between December 15, 2005 and July 3, 2006. The game follows Lost L, a survivor transformed into an incomplete Warhead and forced to consume other Warheads to survive. Gameplay has the character going through an episodic narrative and fighting in command-based battles, with multiplayer allowing different players to fight each other. Western previews of the game's pre-release demo gave praised to its graphics, while a Japanese review at release praised the combat while faulting frequent server connection issues during multiplayer matches.

Code Age Commanders: Tsugu Mono Tsugareru Mono is an action role-playing game released for the PlayStation 2 on October 13, 2005. Taking the role of multiple characters in the aftermath of the Reborn, the player navigates missions fighting opponents in real-time combat, evolving their character over the course of the game and using skills which are inherited by each playable character in turn. Reception to Commanders was positive overall, with many citing its gameplay as enjoyable despite a lack of depth, and praise was given to its story and art design.