Steins;Gate (also known as シュタインズ・ゲート ), which was originally a game by 5pb. on Xbox 360 is a visual novel that made its debut back in 2009. Steins;Gate 0 is a prequel to the original series.
For those who have not played the original game, we have included a plot description below:
Steins;Gate is set in the summer of 2010, approximately one year after the events that took place in Chaos;Head, in Akihabara. Physical locales of Akihabara like the Radio Kaikan building can be spotted in the game. According to Chiyomaru Shikura, who headed the planning of Steins;Gate, Akihabara was chosen because it is an easy place for acquiring hardware parts, which makes it the ideal place for people interested in inventing and tinkering with things. The notion of time and time travelingare the main themes of the game. The concept of cause and effect is featured prominently in the game as the protagonist travels back in time numerous times to perform different actions in an attempt to alter what has happened in the future. Description courtesy of Wikipedia