Blokus
Blokus ( ) is an abstract strategy board game for two to four players, where players try to score points by occupying most of the board with pieces of their colour. The board is a square regular grid and the pieces are polyominoes. It was designed by French mathematician Bernard Tavitian and first released in 2000 by Sekkoïa, a French company. It has won several awards, including the Mensa Select award and the 2004 Teacher's Choice Award. In 2009, the game was sold to Mattel. Gameplay. The game is played on a square board divided into 20 rows and 20  columns, for a total of 400 squares. There are a total of 84 game tiles, organized into 21 shapes in each of four colors: blue, yellow, red and green. The 21 shapes are based on free polyominoes of one to five squares (one monomino, one domino, two trominoes/triominoes, five tetrominoes, and 12 pentominoes). These shapes are the first in the A000105 sequence. The standard rules of play for all variations of the game are as follows: When a game ends, each player counts every square that he or she did NOT place on the board, each counting as a  negative (−1) point (e.g. a tetromino is worth −4 points). The player with the highest score wins. A player who played all of his or her pieces is awarded a 15-point bonus. If the last piece played was a monomino, provided that all pieces of own color have been played, the player is awarded a 20-point bonus instead. Two and three player variations. Blokus rules also allow for two and three player games. In two-player games, each player takes two colors. In three-player games, either one of the players takes two colors or else "the pieces  of the fourth color are placed on the board in a non-strategic way." Expansions and spinoffs. Sekkoïa and its distributors manufacture four additional variants of the game. Blokus Duo/Travel Blokus. "Blokus Duo" is for two players only, and uses a smaller (14×14) board; the piece colors are black and white (originally orange and purple). The two starting squares are placed, not in the corner (as in the original Blokus game), but nearer to the centre. This makes a crucial difference in the flavour of the game, because players' pieces may (and usually do) touch after the first move . Even more than with the original game, Blokus Duo is an offense-centered game; it is also a much purer strategy game than the four-player game, since one is not in danger of getting ganged up on by three other players (as sometimes happens with the four-player version). Blokus Trigon. "Blokus Trigon" uses pieces made up of triangles rather than squares (polyiamonds), and is played on a hexagonal board, a version optimized for three players, but can be played with 2 to 4 players. The same rules apply, meaning that pieces of the same color are still not  allowed to touch each other's edges; however, as it is isometric, a corner touching an edge is allowed. Blokus Giant. "Blokus Giant" is a larger version, with the game board being about square. Blokus Junior. "Blokus Junior" is targeted at younger children. Like Blokus Duo, it is played by two players on a 14×14 board but it uses only a subset of the pieces that have a supposedly simpler shape. There are 12 unique pieces. Each player gets two of each kind, 24 in total. The game also comes with a set of sheets with single-player puzzles, which  show positions in which the player needs to connect two pieces following standard Blokus rules. Blokus 3D. "Blokus 3D", originally marketed in a Mayan theme as "Rumis", uses pieces made up of unit cubes, in every permutation of three and four cubes in three dimensions. Stefan Kögl created "Rumis" independently from Bernard Tavitian, and is thus not related. However, "Rumis" was rebranded into "Blokus 3D" since the "Blokus" brand proved stronger than "Rumis". There is also a major rule change; instead of being required to place pieces so they touch corner-to-corner, a piece must be placed such that  it touches a face of another piece of the same color. Also, a player placing a piece cannot do so if it would create any empty space underneath any part of the piece. The objective is to build one of four different structures, each with its own placement limitations: the Tower, Wall, Steps, and Pyramid. Players attempt to place their blocks such that at the end of the game, when the structure is viewed from above, their color has the most squares showing. Video games. Funkitron developed a PC casual game version of Blokus called "Blokus World Tour". Released  in December 2007, "Blokus World Tour" was similar to the board game version of Blokus, but also featured 16 AI opponents, music and sound effects, and multiple game modes, including a tour mode, quick play, and Blokus Challenges. For some time, there was an official online version of Blokus where visitors could play with opponents all over the world. Mattel discontinued the online game on May 18, 2012, stating it did not meet its playability standards. It is now possible to play Blokus online at Pentolla.com or LeFun.fun. The PlayStation Portable has "", which features characters from "Steambot Chronicles" playing the  Classic, Travel, and Duo versions of the game. A Gameloft developed version of Blokus was released for iPhone, iPod Touch, and iPad in April 2010, featuring the Classic and Duo versions of the game, local and online multiplayer gameplay, and single player tournament mode. A clone named Quadrus, is available since January 2014. As of January 2014, the Gameloft version of Blokus is no longer available from the App Store. Currently, the officially licensed Blokus app is developed by Magmic, and is available for iPhone, iPod Touch, and iPad. This version includes solo play and multiplayer options, integrating the user 's Facebook and Game Center friends and allowing them to compete on a tournament leader-board. Clone video games. There are also open-source derivatives based on the same concept of polyominoes as Blokus, such as: Blokish, Blockem, or Pentobi. Of note, Freebloks 3D is a free desktop version whose online multiplayer is cross-compatible with Freebloks for Android smartphones. Lastly, one free, closed-source implementation is Blokee, playable immediately on the Web with other players and/or AI, and requiring no software download nor account setup to play.