The dark blue block should fill the entire maze without exception in Fill Tracks with its color. The square can only move in a straight line to the first wall. He cannot stop halfway, turn, and so on. This should be taken into account and this is also the main difficulty when solving the next problem at the level. There are only forty levels and their complexity is growing quickly. Special cubes appear in the labyrinths, and when you pass them, empty spaces remain. You can use them to solve problems. Mentally map out a route and then move the square towards your intended goal in Fill Tracks.
