Gameplay
Steins;Gate 0 is a visual novel, where the player reads through the story in the form of passages of text and dialogue, accompanied by character sprites and background art. The story consists of multiple branches, which lead to different endings. As opposed to the original Steins;Gate's single route that runs from start to finish with multiple branch points throughout, Steins;Gate 0 features one branch point near the beginning of the game, where the story splits into two major story branches, which in turn branch again into the different endings; there are in total two main story paths, along with four side stories. The direction of the story is determined based on whether or not the player chooses to answer calls from the artificial intelligence Amadeus, which the player character Rintaro Okabe can communicate with through his cell phone. In addition to Okabe, the player also takes the roles of other characters, mostly Suzuha Amane and Maho Hiyajo.
The player can also use Okabe's phone to interact with his friends through the messaging app RINE: at some points, the game shows a notification indicating that Okabe has received a message, and the player can choose between different messages to send back – either text messages or stickers – temporarily locking the game into a conversation with the other character that changes depending on the player's reply. Unlike the Amadeus calls, the RINE messages do not affect the branching of the story.
Synopsis
Setting and characters
Steins;Gate 0 takes place in an alternative future after the original Steins;Gate's ending, and is set in Akihabara, Tokyo. It follows several characters, including the university student Rintaro Okabe, who, together with his friends Mayuri Shiina, the neuroscientist Kurisu Makise and the hacker Itaru "Daru" Hashida, accidentally have discovered time travel through the use of a microwave oven and a phone – the PhoneWave – which they used to send text messages and digitized memory data back in time. The latter, referred to as "time leaping", essentially transports a person's mind to their body at an earlier point. This has drawn the attention of SERN, an organization that secretly researches time travel, who sent their team of "Rounders" to confiscate the time machine, including the journalist Moeka Kiryu, killing Mayuri in the process.
Within the game world, time consists of alternative histories ("world lines") that branch and re-merge, meaning that events at converging points are destined to happen unless events in the past are changed enough for them to lead to a history so significantly different that it belongs to another cluster of world lines (an "attractor field") with different converging points. One such converging point is Mayuri's death in 2010; to prevent it, Okabe went back in time and caused the shift from the alpha attractor field to beta, where Kurisu was killed and time travel was not discovered. Between the alpha and beta attractor fields lies the "Steins Gate" world line, which is unaffected by their convergence points. Some people can retain memories from the previous world line after a shift, an ability Okabe possesses and calls "Reading Steiner".
Among other characters are Daru's future daughter, the time traveler Suzuha Amane; Mayuri's future adoptive daughter Kagari Shiina; Kurisu's co-workers Maho Hiyajo, Alexis Leskinen and Judy Reyes from Viktor Chondria University; Okabe's friends Luka Urushibara and Rumiho "Faris NyanNyan" Akiha; and Mayuri's friends Yuki Amane, Katsumi "Fubuki" Nakase and Kaede Kurushima.
Plot
The game begins during Steins;Gate's ending, where Suzuha traveled to August 21, 2010 using her time machine to get Okabe to prevent a time-travel arms race leading to World War III; to do this, he needs to stop Kurisu's father, Doctor Nakabachi, from killing Kurisu and bringing her time travel theories to Russia. Suzuha brings Okabe to the moment of the murder, July 28, 2010, but he accidentally kills Kurisu himself due to world-line convergence. Upon returning to the present, Okabe refuses Suzuha's requests to try again, and develops posttraumatic stress disorder.
Nearly five months later, Okabe attends Kurisu's coworkers Maho and Leskinen's presentation of their Amadeus system, which uses digitized memories as artificial intelligence avatars; one avatar has been made based on Kurisu. Speaking with them, Okabe becomes a tester for Amadeus, allowing him to communicate with Amadeus Kurisu through his phone. While trying to change Okabe's mind, Suzuha looks for Kagari, who got separated when traveling to 1998. Maho, who has Kurisu's hard drive, wants to access her theories, hoping to be able to save Kurisu; Russia, other countries, and groups including SERN are also after the theories, and the world line shifts as they monitor activities surrounding Kurisu's theories and memories.
The story splits into two major branches: In the one leading to the ending "Promised Rinascimento", Okabe rebuilds the PhoneWave to help an amnesiac woman identified as Kagari, who has had Kurisu's memories implanted by someone, which gradually overwrites her personality; this inadvertently transports him to 2036 during World War III. Although Okabe had been predetermined to die sometime in 2025, Daru circumvented it by implanting 2011 memory data, as Okabe's body was still alive. Inspired by this and determined to avert this future, Okabe returns to 2010, destroys the hard drive, erases Amadeus, and sends a D-RINE message to the past of this branch, telling himself to "deceive the world and tie the possibilities". The resulting world line is not shown.
