Words With Friends
The game allows players to challenge friends or play against random opponents. The game can search for friends that also have the Words With Friends app installed by browsing the player's contact list and by logging in to his or her Facebook account.
The rules of the game are the same as scrabble. Each player (up to two) receives a number of random letters with which to form words. Letters have values depending on how easy it is to make words with them. Words are placed on the playing board where special fields such as "Double Word Score" and "Triple Letter Score" can be utilized to increase the value of a word. New words have to connect to words already present on the board. When all letters are placed on the board the game ends and the player with most points wins.
The game itself plays in a turn-based fashion, similar to "Play by E-mail" games of yore. A player has infinite amount of time to make his or her turn. Letters can be shuffled around freely and placed on the board to puzzle around. Once the player is satisfied with his or her formed word the play-button is pressed and the information is sent to the other player who now has to perform a turn.
Players can quit the application at any time and the game will continue as normal. If it becomes their turn the app sends a "push message" to inform the player.
It's possible to chat with the opponent in-game. It is also indicated (by a pair of eyes) if the other player is currently in the game or not.
Players can play up to 20 games simultaneously. So one doesn't have to get bored if an opponent suddenly decides to go to work or to bed. The free "lite" version limits the number of simultaneous games, in addition to featuring in-game ads.