The object of Flood-It! is to ‘flood’ the screen with the same color of pixels.
You do so by starting at the top left pixel. From there, you select one of the colored buttons at the bottom of the screen, and your ‘flood’ area will grow to include that color (as long as the color is adjacent to your starting square). You keep selecting colors, your ‘flood’ area grows, and pretty soon almost the whole screen will be one color!
Addictive and Fun!