Lines are black, but they glow red when they touch fire or fire doodles. They will also fade into a blur of colours when disappearing.
Lines are the way the player moves the blots and interacts with interactive objects in Scribble. Lines can be drawn by the player by clicking and dragging the mouse across the screen. Lines can be used to as a platform to allow blots to walk on it. The line can also serve as a wall to stop the blots from going ahead, it can stop or trap enemies, or transport enemies to a place out of reach. It can also react to fire as a wick, which can be used to activate a bomb. Lines can also be used to block lasers. After several seconds, a drawn line will disappear into a blur of colours and then fade away.
The player has a limited amount of ink to draw lines with. This amount of ink a player has is shown at the top of the game screen on a bar. The more ink the player has, the fuller the bar is. If the player runs out of ink, then he/she can no longer draw any lines until one of his/her drawn lines disappears. This will replenish the ink bar.