First up this isn't a game, but a Lovecraft tinted visual novel in which you get to make some choices and do some deducting to propel the story forward. Most of the time you will be clicking to progress the text (although you can switch it to auto) and reading.
There is lots of reading.
I have finished the first 'case,' about 4.5 hours of playtime in. I understand there are 5 in all. While I am unlikely to complete the rest, primarily because it isn't a game (if I am going to read a book, I will read a book) I can tell you a bit more about it.
The story is told from the perspective of the chain-smoking Manager (you never know his name) of the Hermitage, a strange book store with a seeming bent for the supernatural. The Manager is the same, and there are strange goings-on in the lives of the customers that get drawn to the store seeking assistance.
The first case revolves around two students at a posh high school, an art class and a scandal. Plus, the dreams of one of the students, which appear to be visions, and an 'incense' known as Lilac Grass. While there is a tinge of otherworldliness throughout, it ramps up considerably towards the end of the chapter. For me that element was the most appealing bit, but on the whole I thought it was well written and realised.
The Manager never leaves the bookshop, and conducts his part of the investigation through books, an on-line chat room and watching the news on TV, and by plotting relationships on his evidence board. His case files are where the key information is kept, and it will be added automatically as you come across it.
You can also check out his thoughts, always preceded by a deep inhalation of tobacco smoke.
He stays in touch with characters outside the bookstore via text message. Chief among these in the first chapter is his lawyerly friend Scarlet.
Throughout the chapter you will be taken to the case file to select three pieces of learnt information to answer a particular question. You get three chances before 'failing' which I understand leads to a bad ending. Three attempts were plenty, although other reviews suggest it gets harder and a little more opaque as you go.
On one occasion what looked like an eye appeared above the character I was talking to. It enables you to examine a body part more closely, and there is apparently a right time to do so. It didn't make much sense to me, but perhaps it might as you continue.
There is a manga aesthetic to the visuals, and while the scenes are largely static, the characters present at any one time will have a number of poses, and sufficient detail in the expressions to give some 'life' to the scenes. Colour is sparingly but well utilised, and the soundtrack is a jazz infused melange that is rather good. There is no spoken word.
Some interactions use the mouse, but the keyboard was my friend when it came to advancing the text. It saves automatically and you can also save at will.