Objective
Players must place as many of their pieces as possible on the board. When no more pieces can be played, the winner is the player with the largest score. Score is calculated as follows:
Placing a piece
A player's first piece must be played so that one of the piece's squares touches a board corner. Afterwards, a player may place a piece only if it touches another piece of the same color at the corners: two pieces of the same color may not share an edge.
Interface
The board is shown in the left half of the screen.

If the game is not yet over, the upper right shows all players' unplayed pieces. The furthest left box is for the first player, the furthest right is for the fourth player. The bottom right is where the current player's unplayed pieces are drawn.

Once the game is over, the right half of the window will display all unplayed pieces, categorized by their color.

Controls
Artificial intelligence
The computer can control any player; turn this on in the Options >> Artificial intelligence menu. From here, the rudimentary AI's settings can be changed. These settings affect a possible move's rating as follows:
rating = Piece size weight * Chosen piece's weight +
Spaces created weight * # of spaces where another of this player's pieces can be played after the chosen piece is placed +
Enemy spaces weight * # of spaces where an enemy can be placed after the chosen piece is placed
The # of friendly/enemy pieces to check shows how many pieces will be checked when calculating the # of spaces usable by a player. Generally, the weights can be changed without affecting the time AI takes to calculate its move. The # of pieces checked will increase the amount of time the AI takes. 5 pieces is a good number for both of the # of pieces settings.