From Bulbanews, your community Pokémon newspaper.
Game revealed in 2013 finally confirmed for release
Great Detective Pikachu: Birth of a New Duo logo
The new game Great Detective Pikachu: Birth of a New Duo is a cinematic adventure game that will be released in Japan on the Nintendo eShop on Feb. 3, 2016. The game is developed by Creatures, Inc. and published by The Pokémon Company.
From January 27, 2016 to February 29, 2016, the game can be purchased in Japan for ¥1,200, instead of the normal price of ¥1,500. The game is already available for pre-download.
In the game, a boy named Tim Goodman comes to Rhyme City and meets the Great Detective Pikachu. This Pikachu is able to talk and wears deerstalker, a kind of hat associated with Sherlock Holmes.
The game was initially revealed in an NHK Professional: Shigoto no Ryuugi documentary featuring Tsunekazu Ishihara that aired on October 28, 2013, but was unnamed at the time. A trademark was later found for 「名探偵ピカチュウ」 Great Detective Pikachu that was filed in Japan on October 11, 2013.
Image from early development
Note that these subtitles are unofficial.