Short answers, pulled from the story.
P.T. was developed by Kojima Productions, working under the pseudonym 7780s Studio, and published by Konami Digital Entertainment. It was directed and designed by Hideo Kojima in collaboration with filmmaker Guillermo del Toro.
P.T. was released for free on the PlayStation 4 on the 12th of August 2014. Konami announced its removal from the PlayStation Network for the 29th of April 2015, and by May 2015 it was no longer available on the PlayStation Store.
P.T. was a playable teaser for Silent Hills, a cancelled installment in the Silent Hill series. A trailer shown after the game's final puzzle revealed the connection and named Norman Reedus as the protagonist.
Konami removed P.T. and made it impossible to reinstall after Silent Hills was cancelled. The decision drew criticism from writers including Kotaku's Patrick Klepek and Polygon's Nick Robinson, and prompted several fan remakes.
Sony announced in September 2014, during its pre-Tokyo Game Show press conference, that P.T. had been downloaded over a million times.
P.T. won GameSpot's Game of the Month for August 2014, Giant Bomb's Best Horror Game of the year, 'Scariest Game' at Bloody Disgusting's FEAR Awards, and Innovation in Game Technology at the 2014 NAVGTR awards. Polygon ranked it the tenth best game of the year, and Slant Magazine ranked it eighth.