Your goal is to retract all the blue lines into the portals. To do this, click on a white triangle to retract any blue lines that are connected to it. You can't have lines touch each other as you bring them in, so plan your clicks carefully!

In later levels there are new mechanics to untangle, including rotating connection points and red lines that need to connect to a portal in order to be retracted.

You have a limited amount of mistakes before you run out of lives. For a more relaxing experience or to adjust other game options, you can enable unlimited lives in the settings menu!