Astral Chain is a 2019 action-adventure game developed by PlatinumGames and published by Nintendo for the Nintendo Switch. It was directed by Takahisa Taura, who was previously lead game designer for Nier: Automata, under supervision by Devil May Cry and Bayonetta series creator Hideki Kamiya, and character designs from manga artist Masakazu Katsura.

Set in a dystopian future Earth, the game follows the events of a special police task force that protect remnants of humanity from interdimensional creatures and aberrations that invade the planet, with the story centering on the task force's two new twin recruits. Utilizing the titular Astral Chain, the twins restrain and tether the creatures, employing them in combat and investigation, referring to them as Legions. The setting of the game draws heavy inspiration from various cyberpunk manga and anime, while the gameplay combines hack and slash combat with role-playing elements and investigative open-world adventure game sections. The gameplay segments revolve heavily around the simultaneous controlling of two characters; the player character twin and their Legion.

Astral Chain was estimated to have had a five-year long development cycle and follows a slate of previous collaborations between PlatinumGames and Nintendo, with both companies having previously worked together on titles such as The Wonderful 101 and Bayonetta 2. The game was announced February 2019 as a part of that month's Nintendo Direct presentation. Astral Chain received highly positive reviews from critics who praised its dual-character gameplay, world building, presentation, customization, and soundtrack, though it received some criticism for its usage of a silent protagonist. As of December 2022, the game has sold over 1.3 million copies worldwide.

Astral Chain is an action-adventure game where the player assumes the role of a detective from the Neuron special task force, who are tasked with solving cases and investigating incidents that take place on the Ark, the game's environment. Exploring the world, questioning non-playable characters, and examining evidence yields clues and logic puzzles that become leads which further the investigation process. During the course of the game, the player will access the Astral Plane, an interdimensional area where they must traverse hazardous terrain, solve puzzles, and battle enemies, similar to that of traditional video game dungeons.

The player is able to summon a tethered familiar known as a Legion, bound by a chain that is the game's namesake. Legions come in various different forms sporting different abilities that are used both for puzzle-solving and combat. These include: a sword-based Legion with swift blade attacks that can be used to sever circuitry and interrupt enemy attacks, an archer Legion that can target weak points and distant switches, a Legion with powerful punches that can move large objects, an axe-based Legion which generates a shield and can destroy breakable objects and enemy shields, and a K9 Legion that can track scents, unearth hidden objects, and also be ridden for added mobility and evasiveness. The player begins the game with the Sword Legion, capturing the other four over the course of the game. Legions can be swapped at any time during battle, and can also be upgraded via experience points and unlockable skills. On top of the player's own health, Legions have their own individual health meter that gradually depletes while they are summoned, and they are also susceptible to enemy attacks, which depletes higher amounts of their health. Their health regenerates automatically when they're not active. If the entirety of a Legion's health is depleted, the player becomes unable to utilize it until it has restored all of its health.

Combat takes place in real-time, both melee and ranged weapons are used to fight enemies, primarily malevolent creatures called chimeras. Similar to the combat dynamics of Capcom's Chaos Legion, the player can summon the Legion during combat in order to have them automatically fight with the player to create combo attacks. The Legion can be manually directed with the right analog stick, allowing the player to position the Legion for more specific maneuvers. Each Legion also has a unique action that allows the player to take direct control over a Legion's signature ability, such as manually aiming and firing projectiles with the Arrow Legion, or using the Arm Legion as protective armor that can hover over hazardous terrain and attack with a flurry of punches. Additional skills include being able to perform powerful health-restorative finishing moves, unchaining a Legion to summon multiple at once, using the Astral Chain that connects the player to the Legion to bind enemies or as an arresting wire on enemies that attempt charging into the player. The player is also able to utilize the chain in order to zip line out of danger through enemy crowds, as well as crossing gaps and bottomless pits between buildings and platforms.

Completing combos, interrupting enemy attacks, restraining enemies, dodging, and deploying a Legion at the correct moment will offer the player a chance to perform a sync attack, requiring the player to press the left trigger at the right instant, similar to a quick time event. Sync attacks can extend combos, trigger special attacks, bind enemies, and help the player recover from a fall. After performing a large number of sync attacks, the player may fuse with their Legion for a short while to recover health and deal large amounts of damage.

The game features four difficulty settings, allowing the player to switch difficulty between each chapter. The highest difficulty is only unlocked for a corresponding chapter once the player has beaten it once. When played on the two highest difficulties, the game ranks the player based on their individual case performance, giving the player an overall ranking at the end of each chapter. On the two lowest difficulties, the player will not be ranked.