Just never lose vigilance.

Pieces of different color appears on the play area. Your target is get rid of them, having made one-color lines on a vertical, horizontal or diagonal. You can move any piece, if it can reach an empty seat, moving horizontally or vertically on free cells. When lined pieces disappears, new pieces don't appear and you can continue play.
The lined pieces makes a score. The more long line is tne better score. Number of different colors, number of appearing pieces, the minimal line length depends on a mosaic mode.
If the play area is filled entirely, you lost.