Single game allows you to choose your difficulty and set a timer. You can also decide whether you want to play against the computer or a friend next to you, by passing the phone back and forth.

Tournament is the most versatile, with plenty of unlockable content: start at Beginner and work up to Genius. Within each difficulty, there are four levels, also unlockable. Even the first round is tough--but not so tough that I didn't want to keep going back until I beat it.

Solitaire is the simplest mode, letting you practice your skills with no opponent, just in pursuit of a high score.

Basically, there are hours of playability in this game thanks to all of the mode, difficulty, stage, and time limit combinations, as well as the time you spend mastering the unique format. If you're into puzzle games and brainteasers, this is the game for you.