If a tile you just clicked matches any of it's neighboring tiles, then a chain reaction occurs. This chain reaction removes all the neighboring tiles that match the tile you clicked. If you aren't careful, this can create unexpected chain reactions and leave your tiles stranded. You will be able to collect points for this round, but a stranded tile means the board is unsolvable.

For each tile in a chain reaction you increase value of each removed tile by 100 points. For example if you remove two tiles you will score 200 points for each, resulting in a total of 400 points. If, however, you remove six tiles you earn 600 for each, for a total of 3600 points! 

There is also a time bonus available (shown on the counter to the right of the game board) which decreases the more time you take. There is less time available to clear the board with each successive game board.