Main Gameplay Design Patterns
The core mechanic of Bejewelled is to match three or more adjacent jewels of the same colour in a non-diagonal line for points. Matched jewels are eliminated from the play field, "gravity" pulls remaining jewels to the bottom of the screen and replacements fill the space at the top.
Players move jewels by clicking on one and then another adjacent one to swap it with. Jewels can only be swapped with each other if the result of the swap is a completed line.
Bejeweled has two primary game modes; these are named Timed and Normal. In both game modes the overall objective is to maximise the player's score.
Normal Game Mode
In the normal mode players continue creating lines of jewels until there are no more possible lines to match.
Timed Game Mode
The timed mode puts the player under pressure by showing an increasingly fast countdown timer that ends the game when it reaches zero. Creating lines or combos increases the time remaining.
Other Noteworthy Aspects
"More than 25 million copies of Bejeweled have been sold, and the game has been downloaded more than 150 million times." 
PopCap Games