I remember this game but not the name.

At the main menu, there is dark mansion and some buttons like "options" or "start game" 

Main menu looking from this angle: (but the graphic is more different)

After a short cinematic intro full of mysterious music, you starting in a long corridor and you have a flashlight. The lightning sounds outside and everywhere is so dark inside.

A door-shaped black window in the end of corridor.

There is a large hall of the mansion and stairs in the middle of it. Two armored knight decoration left side and right side of the stairs, If you staying and clicking that knights continuously, their eyes will shine red and you will hear death sound, you will be dead.

The hall of the mansion looking like: 

In the bathroom, you see black hairy dark creature looking very creeping face but it disappear when you hold the flashlight on it.

The bathroom creature looks like:

If you click the second door in right of the corridor, you see lot of dolls everywhere in room, they sound weird noises and If you keep staying there, the dolls eyes become red and you are dead.

After your death, it starts again in the same corridor automatically but this time, something is different. The mansion is more clear and bright, more "playable."

If you click the window end of the corridor, it zooming the window and two big eyes show up in 1 second, you dead.

 

[A quote from reddit]

Platform(s): Browser game

Genre: Horror, puzzles

Estimated year of release: 2008-2010's

Graphics/art style: 2D, everything was gradient shaded, pretty amateurish

Notable characters: Spooky and creepy shadow monsters

Notable gameplay mechanics: there isn't W,A,S,D. Just click to move and solve puzzles

Other details: It was a flash game played by a few youtubers. I think it was the first chapter of a series, but only one chapter was made?

There was spooky shadow monsters in the mansion that could maybe kill you?

The game was first person perspective.

The game is not:

• The House. It had colors and wasn't that popular.

• Meat Mansion

• Monster Basement

• Inculcatuon

 

Also:

The visual style is more like Domino House and From Heaven To Hell chapter 3. Even I thought it's the game I'm looking for when I saw that first :-)

Game is black and white styled but some colors pure sharp like blood and water or flowers (red, blue, green)

I remember a crow staying top of some kind of shelf, you can feed it with piece of bread while solving puzzles, when you feed the crow, it gives you (kinda) piece of paper or a key.

There is a television in the living room and when you click that, little puzzle opens up. If you solve the puzzle, a key appears in the middle of screen and you hear some "cheetah" roaring?

If you stay in any room too long, a mysterious shadow ghost/monster will appear and kill you. Monsters are not alone, they seperated to rooms randomly but they are not same thing.

Some creatures attack you instantly when you entered a wrong room/corridor, some monsters just hiding and waiting for you to stay little longer.

 

This is From Heaven To Hell Chapter 3

This is From Heaven to Hell chapter 2

And this is the Domino House