Titled "Urban Legend in Limbo", AKA "2spooky42hoo edition", this game was revealed by ZUN himself in a recent game event. Not much is known about it, except that it will be released sometime in 2015.
Rumors say it will be a "First person exploratory "horror" game" starring Marisa, but they're all but confirmed. Art style seems to belong to Moe Harukawa, the same gal who did the Forbidden Scrollery manga.
>>13573 That screenshot isn't of Touhou 14.5, friend.
>[ZUN] has made "Danmaku Amanojaku Gold Rush", a special version of Touhou 14.3, using less than two days' time. In this game, Seija has got her hands on the 10th rule-breaking item, which can be used to destroy the opponent's danmaku. You will be able to play it at his booth.