Executive producer Chiyomaru Shikura announced on Saturday, March 28, 2015, that Steins;Gate 0 will be a true sequel to the original game and not a spin-off or fan creation. The platform for the new game has not been decided, however, an anime adaptation of Steins;Gate 0 has also been officially announced.
The original game came out on the Xbox 360 back on October 15, 2009 and was ported to the Playstation 3 on May 24, 2012. It has since been ported to Windows PC, iOS, Android, PSP, and PS Vita platforms.
An anime adaptation of the original game aired in Japan from April 6, 2011 to September 14, 2011 and is currently ranked as #2 in the Top 50 Animes of All Time on http://www.myanimelist.net. An OVA as well as a movie were developed as sequels to the anime series. Countless specials have also been released for the franchise.
Steins;Gate 0‘s story will be in the Beta World Line where Okarin fails to save Kurisu. No further details have been given at this time regarding the story of the sequel. No release date has been given as of yet.
Official Site: http://steinsgate.jp/zero/