The lines that have some crossing are marked with bright white, while the ones with no crossings are marked with black. At first, most lines are marked as white. As you progress with the puzzle, more and more lines will be marked as black. At the end, there will be no white lines, denoting a solution.

Tip: Generally, you make a move which reduces number of white lines. All the time you drag a ball, observe the lines for a situation which is better than the current one. Try to keep balls having more lines with them at the center of the screen and balls having fewer lines near the sides of the screen.

In Challenge Mode, you will have a certain objective to accomplish: you have to solve the puzzle within a limited time. The hardness of the challenge is determined according to the game level.