AI: The Somnium Files (/aɪ/ ^ⓘ EYE) is a 2019 visual novel adventure video game developed and published by Spike Chunsoft. Set in near-future Tokyo, the story follows Kaname Date, a detective who investigates a string of serial killings by entering suspects' memories to extract information. Gameplay is split into two sections: first-person visual novel segments and third-person exploration. The plot progresses via branching routes, leading to multiple endings depending on choices made by the player.

The game was written and directed by Zero Escape creator Kotaro Uchikoshi. In contrast to his previous work, Uchikoshi wanted the game to reach a broader audience, and developed it with adventure game fans in mind. Gameplay was simplified, dialogue was reduced, and Yūsuke Kozaki was brought on as lead character designer due to his reputation as a manga artist. The game was first teased in 2017 under the working title Project: Psync, and was formally announced at the 2018 Anime Expo. It released for Nintendo Switch, PlayStation 4, and Windows in September 2019, and Xbox One in September 2021.

AI: The Somnium Files was positively received, with praise for its story, art direction, and characters, while some criticized the game's tone and trial-and-error puzzle mechanics. A sequel, AI: The Somnium Files – Nirvana Initiative, was released in 2022.

AI: The Somnium Files is a single-player adventure video game with visual novel elements, in which the players assume the role of detective Kaname Date. Gameplay is split into two sections: investigating Tokyo and exploring dream worlds, known as "Somnia". The story progresses via branching routes, leading to multiple endings depending on choices the player makes. The plot is not fully revealed in a single playthrough; the player must complete every route to gather the information necessary to solve the mystery. Rather than starting from the beginning of the game after each completed route, the player can skip directly to other chapters–called "Days"–using an in-game flowchart.

Investigation sections take place from a first-person perspective. The player interacts with the environment via an on-screen cursor, similar to point-and-click video games. Date uses his artificial intelligence assistant, Aiba, to analyze crime scenes, reference databases, and receive phone calls. Aiba is also able to augment Date's field of view with optical magnification, X-ray vision, and thermography. Apart from collecting evidence, Date also gathers information via non-player characters in a visual novel format. By selecting characters with the cursor, the player is able to ask questions pertaining to the individual or the environment. During specific action-oriented segments of the game, the player may be presented with quick time events to evade danger or engage in scripted combat sequences.

Somnium exploration plays out in third-person. Date uses a device called the "Psync Machine" to enter the Somnia of subjects who withhold information from him. Within a subject's Somnium, Aiba acts as Date's avatar, taking on a humanoid form. The player controls Aiba, exploring the dream world and solving puzzles to extract information. Somnium puzzles involve examining objects within the environment and choosing an action to perform with them. The player is only able to remain in Somnia for six minutes, with each object subtracting a set amount of seconds from the timer when interacted with. If the player triggers the correct sequence of objects, a "Mental Lock" will open, allowing Aiba to venture further into the subject's subconscious. Depending on the Mental Locks the player chooses to open, the game's story will diverge upon exiting the Somnium.

The game takes place in near-future Tokyo, and follows detective Kaname Date of the top-secret police department ABIS (Advanced Brain Investigation Squad). ABIS, led by Boss, investigates crimes through a method called "Psyncing", in which Psyncers explore the dreams (known as Somnium) of subjects via the Psync Machine. Psyncing is a process that can retrieve clues the subject is subconsciously aware of, but is limited to a maximum of six minutes for the Psyncer and subject's safety. Any longer than six minutes can damage the brain of both the Psyncer and subject, resulting in death. Date is assisted by an artificial intelligence housed in his cybernetic left eye named Aiba, who can communicate with Date, provide him with enhanced vision modes, and hack various electronics. Aiba also assists Date's dream world investigations by acting as his avatar in Somnium.

Date, who lost his left eye and all his memories six years prior, is called to investigate the murder of Shoko Nadami. He finds her daughter Mizuki Okiura at the scene, unable to speak. Date investigates Mizuki's Somnium to find out what she witnessed. Throughout his investigation, he meets several others at the center of Shoko's murder: Renju Okiura, Mizuki's father and Shoko's ex-husband; Iris Sagan, a net idol employed at Renju's talent agency; Ota Matsushita, a fan of Iris; So Sejima, a member of the National Diet; Hitomi Sagan, Iris's mother; and #89, an imprisoned assassin also known as Falco.