Insert the doorknob into the door. Take the battery inside.

Insert the battery into the slot at the back of the cat doll. Turn the doll on by pressing the button on its chest. There will be light coming off the cat's eyes.

Use the doll under the sofa to light up the darkness, and take the yellow key.

Use the yellow key to unlock the chest on the desk (below the eagle picture). Take the antler inside.

Insert the antler into the deer doll on the left of the wash basin. Click on the antler to pull out a bolt-cutter.

Dismantle the yellow key (by clicking on it) to collect a moon-shaped piece.

Use the bolt-cutter to cut the necklace, retrieving another moon-shaped piece.

Look at the doll above the sofa. Insert both moon-shaped pieces into the eyes of the doll. The doll will open up, and take the Key of Clubs inside.

Use the Key of Clubs to unlock the diary. Take the red cellophane inside.

Use the red cellophane on the sketchbook. You should see the numbers 2436175.

Go to the seven-button box above the mirror. The first button you should press corresponds to the number 1, which is the third digit, so you firstly press the third button counting from the left.

Therefore, press these buttons in this order: (counting from the left) third, seventh, fifth, sixth, first, fourth, and second. The box will open and take the battery inside.

Take the battery from the cat doll. Now you have two batteries. Insert both into the remote.

Noticing that the bat picture features the same icon shown on the remote, use the remote on the bat picture. Take the mouse doll behind the picture.

Look at the flower pot on the floor, left of the sofa. At the bottom of the pot there is an electric socket. Plug the mouse doll in.

Inspect the plant inside the flower pot on the floor. Shake it until the switch falls down. Turn on the light using the switch, you will now see something inside the plant. Take out the crumpled paper.

Using the paper as a clue, interact with the three drawers under the basin. Top, bottom, top, top, top, bottom, bottom, top, bottom, and then finally the middle drawer with a square knob. The square knob will come out, revealing that it is a screwdriver.

Inspect the sides of the sofa and find that the sofa is pinned down by screws. Unscrew them all with the screwdriver and move the sofa. Take the towel behind the sofa.

The panel behind the sofa is moveable. Inspect it but you find the hole is too dark. Light it up with the cat doll and find the Key of Spades. (You can remove a battery from the remote and put it inside the cat doll.)

Inspect the white chair near the door. There is a square area in the front of the chair, below the seat. Inspect to find a keyhole, where you can unlock with the Key of Spades. Take the folding knife inside.

Use the folding knife to cut up the pear. There is a six digit clue inside, "XOOXOX". Where did you see something with six buttons?

Inspect the head of the guitar. The clue in the pear corresponds to the strings of the guitar. Press the buttons corresponding to O in the clue and don't press those corresponding to X in the clue. Therefore, press the top left, middle left and middle right buttons, and then go back once to open the guitar. Take the robot body inside.

Use the bolt-cutter to cut the wires holding the framed picture on the desk, on the left of the chest. Take the keycard inside.

Unscrew with the screwdriver the snowman above the fruit bowl. Take the "529 chip" inside. Put the "529 chip" into the slot in the keycard.

Go back to where you find the diary (the bottom right lateral side of the vanity cabinet). Insert the keycard into the receptacle that looks like a face.

The cabinet compartment on the right is now unlocked. Take the robot head inside.

Assemble the robot, using the head, body, and the screwdriver serves as its missing leg.

Go back to the hole behind the sofa. Put the robot in front of the hole. Then, use the remote to send the robot in. (Remember to transfer the battery from the cat doll to the remote.)

Meet the robot on the left-hand-side compartment of the cabinet under the basin. Collect the wrench from the robot. Inspect the wrench to find a clue.

According to the wrench, press the button under the plant with star-shaped leaves (above the mirror), the plant with heart-shaped leaves (above the sofa), the plant with cross-shaped leaves (on the desk), heart, star, and finally cross. Then, a compartment on the desk will unlock and take the clockwork key inside.

Use the clockwork key in the keyhole where you find the robot head, which is the right compartment of the cabinet under the sink, where a set of skeleton is inside. After you turn the key, take the cog that pops out.

Also find the Key of Diamonds behind the skeleton (or, as revealed, a picture of skeleton).

Unbolt the eagle picture above the desk. Take the pencil inside. Insert the cog into the mechanism and press the button.

Take the broken picture frame that falls down. Take the faucet hidden behind the picture frame.

Insert the faucet into the basin. Now you can turn on the water and wet the towel.

Use the wet towel on the left side on the desk, where there is a dirty area. It reveals a picture of several fish, but is there something wrong?

One of the "fish" is actually a keyhole. Insert the Key of Diamonds to unlock left drawer of the desk. Press the button inside, and now the lights are off.

Inspect the glowing spot on the right side of the mirror. Unbolt the lamp with the wrench, and find a red rod inside.

Insert the red rod into the clock near the door. Press on the red rod and now you can operate the clock. Is there a clue for the clock puzzle?

The round window, now with a triangle base and "rabbit ears", is the clue.

If you put all three of the clock's hands to 11, it will form the same shape as the window. Then, press the top red rod. Lights are now back on, but not only that. One light that wasn't on is also now on.

Inspect the lamp on the right of the mirror. Put the lampshade back, and you see three symbols.

Use the pencil on the diary. It says the first symbol equals 3.

The second symbol is the picture on the desk, upside down. So it is "61", not "19".

The third symbol is the eagle, and looking at the eagle picture, you can see that the pattern inside the eagle is the same as that of the "529 chip".

So, the three symbols correspond to the six-digit number "361529". Now unbolt the panel on the door and put this number in. Take the hammer.

Using the Broken Windows theory, break open with your hammer the broken picture frame. Inspect the hidden picture inside.

The picture hints at a spot left of the door, under the clock and above the pot of grass. Inspect that spot to see a dent. Break it open with the hammer and take the Key of Hearts inside.

Now that we have broken so many things, using the Broken Windows Theory, we should just break the mirror for good measures! Take the M-shaped key inside the mirror.

Use the Key of Hearts to unlock the right drawer of the desk. Take the disc inside.

Insert the disc inside the slot above the sofa. Insert the M-shaped key into the keyhole to the right. Turn the key to turn on the mechanism, which shows the Heart, the Spade, the Club, and then the Diamond, before showing the puzzle.

Look at the "teeth" of the keys. They are actually letters. Therefore the answer of the puzzle is "SEKY".