Find the chest on the top left to grab some matches. Use one to light up the room. Interact with the TV a few times. There is a 2/9 chance that a key will spawn to the left. Grab it to leave the room. 

When exiting, you'll see a cat moving around. The cat's meows will damage you in various rooms. You'll need to use beds to recover your HP. You can also use healing items, but since they are limited I recommend only using them when you're far away from a bed. If you find the cat too hard to deal with, I added a cheat code which disables it (check out README.txt for it)

Grab the key in the fireplace. This area also has a clock which you can use to save as many times as you wish.

Head down and to the left to find an optional area with a bed, and a cheat keycard. Cheats are listed in the README.

Go back to the main hallway and go down to find a blue carpeted hallway. Go left to enter the kitchen.

In the kitchen, you will find a fridge. Interact with it 4 times to get the latern. If you equip the lantern, you'll be able to always see! Say goodbye to matches.

Go down to enter a library. The books are irrelevant to solving any puzzles. Instead, investigate the two statues. Exit the library and go to the door on the right. You have the idea to find other hidden switches to open the door. These are two statues across the map, explore for them.

When unlocked, you'll find a bunch of flowers. To solve, hit the bottom left, then middle, top right, top left then bottom right. Flip the switch.

In the red hallway, go to the area in the top right. You'll hear some strange singing and a key will be dropped. Enter the door on the right. You'll find a dead bird. Interact with it twice to get the Bird Key. Enter the next room. Enter the passcode 0415. (The code the first key had written on it.)

You'll find an area with multiple statues. Hit the green one to unlock the door.

Investigate the toilet multiple times to get a key. Investigate the wall beneath you to discover a hidden door which you can use the key with.

In the room, find a holy candle beneath a barrel. Equip it. Fall down the pit, and find a key. A monster will spawn, but your holy candle will fend it off. A key will fall down near the boiler. Unlock the door and you'll enter a room with water on the ground. Grab the key from the right, then go back from where you came.

Climb up and go down. You'll be back in the room with all the dead birds. Go back to the blue hallway and open the top right door. Interact with one of the birds and you'll get a new key. Go back to the area with all the water on the ground.

Watch out! Approaching is a bunch of flames. Dodge them by hugging one of the walls and keeping close. Afterwards, you'll find two paths. If you do not do anything, you will be killed if you enter the left or right doors. Interact with the left painting and go to the left door.

You'll find a chest which will open a monster's cage. When you return, interact with the right painting and enter the right door and obtain a pistol. EQUIP the gun. Press A to fire. In order to leave you'll need to kill the monster. Only one of them is able to take damage, and when they die all of them die. Once you're done, leave the area.

There are now monsters all over the mansion. Dodge all of them and head back to the main red hallway, to the bottom right door (next to the statue)... congrats, you have completed the game!