Copyright (c) 1966 Parker Brothers Publ. 

This game is played on an empty 10x10 square board:

Each player starts with a set of 12 pieces (the pentominoes) off board:

TURN - On each turn, each player drops one of his pieces provided that:
It occupies only empty cells,
It cannot create an isolated area (considering only orthogonal connections) of less than 5 cells.
The piece can be flipped or rotated before the drop.
GOAL - Wins the player that places the last piece.
An invalid move

After the white move, the black drop is illegal, since it created an isolated area of 2 cells.

Some notes from this website (where you can find much more information): Ironically, although the opening is the most difficult phase of the game to understand, it is possible to throw away the game on the first move of a two-player game! If the first move occupies either one or two of the four central squares, then in almost every case, the opponent can respond by making the rotationally symmetric move. I call this the "symmetric strategy." Once the central region is closed off, White cannot break symmetry, and Black will make the last move. [...] The most important goal to aim for is to fence off a move only you can make, and which your opponent cannot block. Such a region is usually 5 squares in size, but could also be a portion of a larger region (10 squares or more). Once you get this reserve move, if you can prevent your opponent from doing the same to you, a win is assured. Naturally, you'd want to keep that move in reserve until the end. A reasonable secondary objective in the opening would be to  reduce the opponent's responses as much as possible, while reducing your own future choices as little as possible.