It is a game to erase monsters of the same color.
Rules are ...
The monsters of the same color that touch the monster you chose will disappear at the same time.
The more monsters you disappear at the same time, the bigger the score will be.
The monster that was on the disappearing monster falls down.
When a vertical monster disappears, the monster on the right adjacent column moves to the left.
The game ends at the time when there are no monster deletable.
As a special rule, you can change the color of the monster. (Only once for each color)
The time to completion and the score will be registered in the game center.