STEINS;GATE is the award-winning time travel science-fiction interactive visual novel developed by 5pb. and Nitroplus.
It is widely considered to be one of the finest Visual Novels ever made.
STEINS;GATE follows a rag-tag band of tech-savvy young students who discover the means of changing the past via mail, using a modified microwave. Their experiments into how far they can go with their discovery begin to spiral out of control as they become entangled in a conspiracy surrounding SERN, the organisation behind the Large Hadron Collider, and John Titor who claims to be from a dystopian future.
Interaction with the game takes place through the “phone trigger” system, where the player can receive calls and text messages and decide whether to reply to them or not, changing the outcome of the game’s plot.
Source: The Game Website.