Steins;Gate, is a sci-fi adventure game by 5pb. and Nitroplus which also published as visual novel, then adapted into manga and then anime in 2011.
Steins;Gate (S;G) actually sets in the same timeline as Chaos;Head, considered the prequel to S;G.
S;G is a drama, psychological, mystery, science fiction, and thriller that talks about time travel theory with lots of discussions that made me keep on watching.
It starts off with Rintaro Okabe, the mad scientist of the series who also calls himself Huouin Kyoma, claims the world he’s living is a conspiracy theory and his life is in jeopardy for knowing the secret.
With him is Mayuri Shiina, the supporting female character who turned out to be the major reason for the time travel events.
*L>R – Daru, Kurisu Makise, Ruka, Feris Nyannyan, Amane, Moeka, Mayuri Shiina, and Rintaro Okabe*
It discussed about alternate timeline, parallel universe, and butterfly effect, the topics of time travel.