Shin Megami Tensei IV: Apocalypse is a 2016 role-playing video game developed and published by Atlus for the Nintendo 3DS. It is the sequel to Shin Megami Tensei IV, set in a post-apocalyptic alternative world. The game is part of the Shin Megami Tensei series, the central series of the Megami Tensei franchise. The game features gameplay mechanics from previous Shin Megami Tensei releases, such as the Press Turn battle system, where players and enemies fight and exploit weaknesses, allowing either side to gain additional turns or lose them.

The story is set in an alternate timeline of Shin Megami Tensei IV, and focuses on the demon hunter Nanashi, a silent protagonist who dies and is resurrected by the demon Dagda in exchange for becoming his "godslayer". Development began shortly after the release of Shin Megami Tensei IV. It received generally positive reviews from critics, who praised the game's feel and quality of life changes from Shin Megami Tensei IV. The game sold approximately half of the debut sales for Shin Megami Tensei IV during its first week, which was still considered successful for a non-numbered series entry.

In Shin Megami Tensei IV: Apocalypse, the player controls the demon hunter Nanashi as they explore locations including a post-apocalyptic Tokyo and the medieval kingdom Mikado. The setting, most demons, and a large number of mechanics are carried over from the game's predecessor Shin Megami Tensei IV. The player navigates local environments with a third-person perspective, with the aid of an overhead worldmap. Battles take place from a first-person perspective, and are triggered either through story sequences or encountering enemy sprites in the environment. The party gains experience points and levels up by winning battles and completing quests. When the protagonist gains a level, he is given skill points allotted to five different statistics which alter how he performs in battle. When in battle, Nanashi has a party of three demons and a "Partner", an automated companion with a unique demon roster, giving them a different set of abilities.

During battle, both player and enemy actions are governed by the turn-based Press Turn System, a battle system carried over from previous entries in the Shin Megami Tensei series. The system revolves around exploiting physical or elemental weaknesses, and landing critical attacks: if a character strikes another character's weak point or deals a critical hit, the party gains an extra turn, while if the attack is absorbed or blocked, they lose their turn. If a party member from either side ambushes the enemy, strikes a weakness or gets a critical hit, they may enter "Smirk" status: Smirking temporarily increases a character's damage, eliminates their elemental weaknesses, and guarantees their next attack will land as a critical hit. It also grants temporary bonuses to a character's skills.

In addition to fighting demons, they can also be persuaded to join the player's side, as the only way to gather a party. If a demon does not immediately attack, it is open to negotiation and can be persuaded to join. If a demon agrees to join but Nanashi's level is too low, another demon is called in to take the first demon's place. Once part of the party, demons can engage in dialogue, and grant skills and bonuses to Nanashi. Certain abilities also effect the demon's health, magic and elemental resistances, with certain attack types either inflicting penalties or granting additional status buffs. Two or more demons can be fused into a new form, granting new abilities. During fusion, players can choose which skills are retained and which are discarded.

Shin Megami Tensei IV: Apocalypse takes place in 2038 in Japan, within the same setting as Shin Megami Tensei IV. Twenty-five years prior, a devastating war was waged between the league of angels and the demonic armies of Lucifer. To protect Tokyo from damage, a great rock dome was created. While it protected Tokyo, resources became progressively scarcer over the following years, while angels and demons ruled over humans.

The story incorporates folklore from ancient religions, including deities such as Krishna, Maitreya, Odin, and YHVH. The game's silent protagonist is the teenage demon hunter cadet named Nanashi. He is killed while on a demon hunt and he is contacted in the afterlife by the demon Dagda, who offers to restore the protagonist to life in exchange for becoming his "godslayer". When returned to life, he is manipulated by Dagda and Odin into freeing Krishna from a prison made by YHVH, who forms an alliance of various polytheistic deities called the Divine Powers, for the claimed purpose of saving humanity and opposing Merkabah and Lucifer. The storyline takes follows from the beginning of the previous game's neutral route: protagonist Flynn and his companion Isabeau have chosen to ally with the people of Tokyo, while Flynn's former companions Jonathan and Walter have respectively become the hosts for Merkabah, leader of God's angelic forces, and Lucifer, ruler of the demon hordes. There are multiple endings, with both of the primary endings being neutral; the game's law and chaos endings serve as abridged conclusions to the story.

In post-apocalyptic Tokyo, Nanashi is killed by demons. In the afterlife, a demon named Dagda offers to resurrect him in exchange for his service as a Godslayer. Shortly afterward, Nanashi and his friend Asahi are manipulated into unsealing Krishna, a ruthless deity who intends to destroy the universe and create a new one free of YHVH's influence. Krishna takes Asahi hostage in order to force Flynn to surrender to him, intending to force Flynn to become his own Godslayer. He also unleashes the monstrous serpent Shesha to begin harvesting human souls for his plans. Nanashi and Asahi set out to defeat Krishna and Shesha.