Click on any row or column to make a move. All the top balls of the same color as the central one are removed, and the following ball (if any) swaps colors with the big one.
Check in-game instructions for better visual explanation of the rules.
In easy, normal or hard mode - a new ball appears each turn, so no need to hurry - think over your strategy.
In arcade mode - a new ball appears each second, so it doesn't matter how many moves you make to remove balls - just click as quickly as possible to remove them!
Compete for high scores in each mode. If you're master of the game and score 10.000 points, you have a separate "Elite" highscore table with the least number of moves (time) to reach this score. Mere mortals compete for the highest score in each mode.