Tile-matching video game casual games, tile-matching games are designed to be easily accessible and easy to play, which conflicts with a traditional video gaming ethos that demands games to be challenging and punishing. Match-three games are NP-hard when generalized to an n × n playfield and played such that the player knows in advance all the tiles that will appear, with no random chance involved. In particular, it is NP-hard to determine: Tile-matching video game A tile-matching video game is a type of puzzle video game where the player manipulates tiles in order to make them disappear according to a matching criterion. In
Challenge (Scrabble) has not seen a single drawn tile yet, in order to consider whether to challenge. To do this, the player simply announces, "Hold," which prevents the opponent from drawing replenishment tiles for 15 seconds (but may draw thereafter, keeping those tiles separate). The player may decide to rescind the hold, or challenge the play. Scrabble and Scrabble-like game sites on the Internet such as Yahoo! Games' Literati, Internet Scrabble Club and Lexulous offer automatic verification as an option, which makes it impossible to play an invalid word. The Facebook version of Scrabble and Zynga's mobile game Words With Friends make