Steins;Gate 0

Steins;Gate 0 is a visual novel published by Spike Chunsoft for the Nintendo Switch in 2019. It is a sequel to Steins;Gate Elite.

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 Steins;Gate Elite'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.

Plot
The game begins during Steins;Gate Elite'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.

The first major branch has two side branches: In "Recursive Mother Goose", Okabe and Mayuri trace the origin of Kagari's only memory, a song they learn Okabe originally sung as a child after Mayuri's grandmother's death. After nearly being hit by a truck, Kagari regains memories, including having escaped a facility she was held at in 2005. Mayuri intends to time travel with Suzuha to reach Steins Gate, but Kagari takes Mayuri's place as she fears not meeting her in Steins Gate. In "Twin Automata", Maho hides in Faris's apartment after a kidnapping attempt, and befriends Moeka. Noticing that somebody is trying to steal Amadeus, Leskinen and Maho go to lock down the data, but they are ambushed by Reyes, who shoots Leskinen and tries to make Maho give her the Amadeus access codes. Maho decides to erase Amadeus rather than give it up, and she is saved when Moeka shoots Reyes. While Amadeus Kurisu is being deleted, a Kurisu apparently from another worldline takes her perspective. She calls for help, and tells Maho that Steins Gate is real, and tells Maho her laptop password is related to Piano Sonata No. 10, a piece by Mozart that had been the theme for this ending branch. Returning home, Maho figures out Kurisu's password from this hint and finds her research.

In the second major branch, leading to "Vega and Altair", Okabe stops testing Amadeus. If the "Promised Rinascimento" ending was completed first, a D-RINE message will appear early into the branch with its cryptic message: "deceive the world and tie the possibilities", but its origin is unknown. He and Maho are followed by groups who want Kurisu's theories, and Kurisu's hard drive is destroyed in a skirmish. Daru and Maho secretly rebuild the PhoneWave in an effort to save Kurisu, but is unable to complete the test due to missing components; Okabe tells them that saving Kurisu means sacrificing Mayuri, which Mayuri overhears. She decides to travel back in time with Suzuha to convince Okabe in 2010 to save Kurisu after failing in his prior attempt. However, Leskinen appears, revealing that he works for the intelligence agency Strategic Focus and intends to steal the time machine. Mayuri and Suzuha attempt to flee in the time machine, but it is hit by a rocket and destroyed. In the aftermath, Okabe discloses the missing components to Daru and Maho to complete the PhoneWave, thus allowing him to time leap to an earlier part of the day, and works to ensure Mayuri and Suzuha's successful time travel. Surrounded by Leskinen's men, he declares that he will find a way to Steins Gate.

The second major branch has the side branch "Gehenna's Stigma", where Maho is caught eavesdropping on Reyes and Leskinen, hearing that Leskinen thinks Okabe hides information. Leskinen uses Maho: She meets Okabe, who tells her about time travel provided that she does not try to save Kurisu. After he reveals where Suzuha's time machine is, Maho suffocates him; when waking up, he is tortured for information by Leskinen. Wracked with guilt for betraying Okabe, Maho makes an unsuccessful attempt to save Kurisu in her own way. World War III begins, Daru flees Akihabara to develop the time machine, and Okabe gives up on reaching Steins Gate.

The final ending, "Milky-way Crossing", only appears after completing the "Promised Rinascimento" and "Vega and Altair" endings. It is set in 2025 on a world line similar to, but not the same as, the one from "Vega and Altair". Okabe sends a D-Mail video to his 2010 counterpart, instructing himself how to save Kurisu and cause the world line divergence into Steins Gate, thus setting the events that would play out as the True End route in the previous game. He then leaves in the time machine to find Suzuha and Mayuri, and bring them safely back to 2025.