Serial Experiments Lain

The game was designed as a "network simulator" which the player would navigate to explore Lain's journey between real life and online life. The creators themselves did not describe it as a game but as "Psycho-Stretch-Ware", incorporating visual novel and non-linear multimedia elements; the gameplay is limited to unlocking pieces of information and then reading/viewing/listening to them, with little or no puzzle needed to unlock. Lain distances itself even more from classical games by the random order in which information is collected. The aim of the authors was to let the player get the feeling that there are myriads of information that they would have to sort through and that they would have to do with less than what exists to understand. As with the anime, the creative team's main goal was to let the player "feel" Lain, "to understand her problems, and to love her".

Lain Iwakura is a quiet, withdrawn girl who has begun experiencing auditory and visual hallucinations, as well as recurring nightmares. Her parents arrange for her to see psychiatrist Toko Yonera, who works at Tachibaba, a research center dedicated to mental disorders and the psychology of communication. Lain is the first patient in Toko's career; while Toko genuinely strives to help her, she is simultaneously under immense stress due to a heavy workload of routine tasks and difficulties in her personal life.

Toko tentatively diagnoses Lain with a delusional disorder, yet she maintains the belief that Lain is fundamentally sound and that the true source of her psychological trauma lies in her nightmares. The therapy sessions yield some positive results, and Lain begins to return to a semblance of normal life. However, she soon becomes the target of bullying by her friend Kyoko and the entire class after catching the eye of a boy whom Kyoko had a crush on. Lain drops out of school and begins to intensively study computer programming and psychiatry using a computer gifted to her by her father.

Unlike the anime, the game drew little attention from the public following its initial release. While praised for its visuals, it was criticized for its lack of gameplay, interface, interminable dialogues, absence of music, and long loading times. In 2008, an English fan translation project of the game's script began, eventually being released as a PDF in 2014. By 2021, a renewed wave of interest in the game had formed, coinciding with the release of lainTSX, an unofficial web browser-based port of the English version of the game, utilizing webGL.

A review of the browser version for The Michigan Daily described it as "raw and realistic in how it showcases mental health, but also overflowing with empathy for the matter, something a lot of representation misses." In 2026, a decompilation of the game was released, reconstructing its source code in C that rebuilds a byte-identical copy of the original executable, along with a native client for Windows, macOS and Linux that runs the game without an emulator using data from the player's own discs. The game has been cited as a precursor to later titles such as Her Story and What Remains of Edith Finch. By 2024, the game's value had risen to an extent that an unused, sealed copy of the game was valued at around US$3400.