Tap the screen to slow down those vertical dashes. Don't make a dash collide with another dash.

On a brown map, you have a horizontal line going left, and a vertical line going downward. Each of these lines is broken into white fragments of different sizes, all moving at a constant speed. You do not control the horizontal line; only the vertical one. The goal is to slow down the vertical line in such a way so as to let a vertical line component pass through a gap in the horizontal line.