The 8th floor is mainly a Tutorial, if you follow the instructions on the screen you should have no difficulties to reach the S rank.

• Room 1 > 03 Steps
  
• Room 2 > 09 Steps (+6 steps)
  
• Room 3 > 16 Steps (+7 Steps)
  
• Room 4 > 23 Steps (+7 Steps)
  
• Room 5 > 25 Steps (+2 Steps)

Repeat the actions learnt during the 8th floor and listen to the robots hints.

• Room 1 > 05 Steps
  
• Room 2 > 08 Steps (+3 Steps)
  
• Room 3 > 14 Steps (+6 Steps)
  
• Room 4 > 26 Steps (+12 Steps)
  
• Room 5 > 38 Steps (+12 Steps)
  
• Room 6 > 48 Steps (+10 Steps)

As usual, take the time to read the instructions given by the robots.

• Room 1 > 03 Steps
  
• Room 2 > 10 Steps (+7 Steps)
  
• Room 3 > 19 Steps (+9 Steps)
  
• Room 4 > 40 Steps (+21 Steps)

In order to limit your steps, you need to learn two new techniques which are particularly useful with the elevators. Those two techniques are often used together and aren't explained by the robots.
- You can place multiple lights on the first lantern of a group, then move on top of an elevator before dragging the lights from lantern to lantern to activate the elevator.
- It is possible to absorb the lights while dragging your lights to activate an elevator. For doing this, place the lights on the first light of a group, then press S to prepare yourself to absorb the lights. Once ready, drag the lights to activate the elevator and releases S, you should have absorbed all the lights around, including the first one of the chain activating the elevator.
To make it easier to understand, I made a gif to show the process.

Robots won't teach you anything more, but with what you already learnt, this one shouldn't be a problem.

• Room 1 > 10 Steps
  
• Room A > 24 Steps (+14 Steps)
  
• Room B > 36 Steps (+12 Steps)
  
• Room C > 53 Steps (+17 Steps)
  
• Room D > 68 Steps (+15 Steps)
  
• Room A > 71 Steps (+3 Steps)

When in doubt, press F to see the range of Luz and the lanterns. You have now access to the blue light. Don't forget to speak to the robots.

• Room 1 > 06 Steps.
  
• Room 2 > 24 Steps (+18 Steps)
  
• Room 3 > 39 Steps (+15 Steps)
  
• Room 4 > 58 Steps (+19 Steps)
  
• Room 5 > 72 Steps (+14 Steps)
  
• Room 6 > 92 Steps (+20 Steps)
  
• Room 5 > 93 Steps (+1 Steps)

It's pretty easy to get lost here, don't hesitate to restart if you think you missed something important.

• Room 1 > 11 Steps +0 Light
  
• Room 2 > 24 Steps +0 Light (+13 Steps)
  
• Room 3 > 44 Steps +1 Light (+21 Steps)
  
• Room 4 > 59 Steps +0 Light (+14 Steps)
  
• Room 5 > 80 Steps +1 Light (+21 Steps)
  
• Room 6 > 105 Steps +0 Light (+25 Steps)
  
• Room 7 > 109 Steps (+4 Steps)

There have been a version change between the moment the Chinese guide has been made and now. The current solution forces you to to do 4 more steps in the Room 4 as there is one lantern missing.

Spinning around. Divide and Conquer !

• Room 1 > 22 Steps
  
• Room 2 > 33 Steps (+11 Steps)
  
• Room 3 > 57 Steps (+24 Steps)
  
• Room 4 > 63 Steps (+6 Steps)
  
• Room 5 > 95 Steps (+22 Steps)
  
• Room 4 > 101 Steps (+6 Steps)
  
• Room 5 > 103 Steps (+2 Steps)

The room 4 requires you to be particularly fast to activate the first wick, here is a gif so you can see how you're supposed to do that.

"The Floating Rocks of Mystery" will give you a new useful power.

• Room 0 > 02 Steps
  
• Room 1 > 09 Steps (+7 Steps)
  
• Room 2 > 20 Steps (+11 Steps)
  
• Room 3 > 35 Steps (+15 Steps)
  
• Room 4 > 60 Steps (+25 Steps)

Be patient and think ahead before doing anything. Before trying to get the restarting achievement, train with the lantern, one off placed and you have to begin again.

• Room 1 > 15 Steps
  
• Room 2 > 35 Steps (+20 Steps)
  
• Room 3 > 59 Steps (+24 Steps)
  
• Room 4 > 83 (+25 Steps)

I'm not done myself with the game, but having a look at the other guides, I thought it was helping a little too much and I would rather prefer to know how many steps take each room to find the best solution on my own. Though, if you want me to make a video for each floor, you only have to ask.