An essential component in the game is the "Senses Sympathy System" ("SSS"). Throughout the game, the player is given a chance to adjust their impressions ("Senses") of the characters (including the characters that they are taking the role of) using sliders. The SSS is based on the Enneagram of Personality, with each of the main characters of the story representing one of the nine different types. At scenes where the player is allowed to give their input - referred to as "branches" - the enneagram figure will show up on the screen; however, only characters that are relevant to the scene can have their Senses be adjusted. How the player interacts with the SSS at the branches directly influence the progress of the story. When the enneagram figure shows up, the color surrounding the outline of the graph signifies the importantance of the player's input. There are three different colors: blue, yellow, and red. Blue are branches that can influence a character's overall favor but are generally not important to the story; however, skipping too many blue branches can be detrimental later on. Yellow are branches that affect a character's actions and change how the story advances. Finally, red are branches in which deciding incorrectly will lead to an undesirable outcome, making the inputs at these branches critical.
Each story scenario has multiple endings based on the results of the SSS up to certain points in the game. In the cases that the player gets a "bad ending", a hint is given which would give tips on how to avoid it; should the player not want the hints, they can be turned off in the options menu.
Synopsis
Setting
Root Double takes place at a fictional location in Japan named Rokumei City, a combined city and research hub with 180,000 residents. In the world of Root Double, humans who have extrasensory perception abilities has become commonplace. From its initial discovery, researchers named these abilities "Beyond Communication" ("BC") and the people who have BC "Communicators". Due to the lack of knowledge and fear about BC, Communicators are discriminated against by ordinary people; as a result, the Japanese government enacted laws to help protect Communicators, turning certain cities - including Rokumei - into Communicator-friendly territories where Communicators could live together and be given guidance. The residents of the city cannot interact with the outside world unless given permission by the government; in exchange for this, and for giving up their privacy, they receive many benefits such as exemption from taxes and access to high-quality medical facilities.
Rokumei City is home to over 300 research facilities; the largest one is named the 6th Laboratory of Atomic and Biological Organization ("LABO") and conducts nuclear research.
Main characters
Depending on the story route being played, the player takes on the role of one of two protagonists.
In route A, the protagonist is Watase Kasasagi. Watase is the captain of the rescue squad for Rokumei City. Early on in route A, Watase suffers from amnesia and does not remember who he is. Two of his squadmates come to his aid: Kazami Tachibana, the lieutenant who is calm and collected with a strong sense of responsibility and Jun Moribe, a cheerful rookie member and is known for her passion in wanting to become a hero. Through the two, Watase learns that he is calm and intellectual who, while strict, is able to make rational choices. Watase often hears a hallucinatory voice in his head; unsure of what it is, he listens to its guidance in hopes of finding his lost memories. Along the way, the three meet two other people: Ena Tsubakiyama, an eloquent high school teacher at Rokumei Academy who comes off as aggressive and Keiji Ukita, a hard-working researcher at LABO who believes strongly in justice.
In route B, Natsuhiko Tenkawa is the protagonist. Natsuhiko is a high school student and resident of Rokumei City who tends to avoid getting involved with other people and would prefer to stick to his everyday daily routine. Natsuhiko is supposedly a high level Communicator but is unable to use the fundamentals of BC and has a hatred for it. His mother, Miyoko Tenkawa, is a scientist at LABO and is rarely ever home, causing Natsuhiko to be emotionally distant from her. He has two close childhood friends: Yuuri Kotono, a quiet girl who lives with Natsuhiko and does not ever leave the house due to posttraumatic stress disorder (PTSD) and Mashiro Toba, an energetic girl who takes care of Natsuhiko in the absence of his mother, goes to the same school as him, and is a competent Communicator. One day, Natsuhiko's mother introduces Louise Yui Sannomiya to the three; nicknamed as "Salyu", she is a young genius who has skipped two school grades but has a difficult time reading the emotions of others and appears actively conscious of Natsuhiko.
