2) Take a look at the 2 doorway boxes. There is no way but push one of them outside in order to get out. So you need to find a way to push one of them out. Now push the center two boxes. This step is super tricky. If you not push this two, it may never be able to finish the game.
3) Pushing one step down then you can find a way out.
4) Now we spread the boxes in two group. You need to finish the upper group so that you have enough space to solve the lower group. Push one of the box from right in the upper group and push down another box 1 step.
5) You now have space to clean some boxes at top. Push down one box from the top and push another box toward right 1 step.
6) It is clear that you can finished one box to top location.
7) It is an easy job to finish those top group boxes. Next step is push one box in the lower group from right side so as to let a way for the boxes out (In order to move boxes to the bottom position)
8) You can push some boxes temporally up the empty space. Remember to finish the bottom two first.
9) After clean the red boxes, let's go for the yellow. Push one box as follow. Although the map seems symmetric upper and lower, but due to the wall at the left most border, you need to push this. (And also, that's why you push those two boxes in red group center at start.)
10) Then you can clean those boxes outside the door.
11) Now you need to go inside the center corridor. Go and push boxes at bottom as follow:
12) Clean some boxes again.
13) Push two boxes at follow. If you push the other two at center, you will find that you don't have a way to go to top left corner.
14) Push two boxes up.
15) Clean some boxes, and push a box as follow. You can see it seems symmetric now.
16) To solve the boxes as the top left corner pattern, push the center box toward right 1 step. And up to now, it is obvious...
17) Done~
