Shin Megami Tensei IV is both a numbered and spin-off title in Atlus' long-running "MegaTen" RPG series. Players assume the role of a "Samurai" (default name Flynn), one of the sworn protectors of the feudal Kingdom of Mikado granted the ability to defeat and summon demons through use a mysterious gauntlet equipped with a sentient AI program. Flynn and his fellow Samurai are initially tasked with rooting out the mysterious "Black Samurai" said to be cause of a demonic invasion threatening Mikado, leading to a journey through the depths of Mikado that may reveal more than the Samurai bargained for.
While the game is intended to be a spin-off from previous MegaTen titles set in an all-new universe, SMTIV still retains many themes and gameplay elements central to the main series. Players will assemble a team of demonic allies by coercing them to join their cause or by creating them through the process of "fusion", then do battle against other demons encountered in dungeons that are now presented from a third-person perspective. This allows players to view their surroundings as they explore the dungeons, and enemies encounters are also now visible on the map as hostile units that will try to engage the player party; players can attempt to aim for a pre-emptive strike on enemies by literally attacking these units in the dungeons before they make contact.
Another important game element is the player's "alignment" that shifts between the classic Law, Neutral and Chaos archetypes based on decisions and actions make the player throughout important moments of the game, or even in general circumstances. This will have a direct effect on how the story will play out during the endgame sequences, as well as the ending the player will earn.
The game adopts the "Press Turn" gameplay mechanic previously used in SMTIII: Nocturne for the PS3, where using attacks and skills that are effective against enemies will reward the player party with extra turns and buffs.
SMTIV is also the first numbered entry in the MegaTen series since 2003's SMTIII: Nocturne, and the setting and story were initially conceived by celebrated MegaTen series artist and designer Kazuma Kaneko. However the actual character art and designs were produced by Masayuki Doi, who previously worked on Atlus' Trauma Center series of games. The game's soundtrack was jointly produced by a team consisting of Ryota Koduka, Kenichi Tsuchiya, and Toshiki Konishi. SMTIV enjoyed further collaboration from a variety of artists for the designs and artwork used by the game's catalog of demons.