"Concentration" was NBC's longest running game show, lasting from 1958 until 1973 in its original version. This home version game by Milton Bradley dates from 1961, just three years after it began on television. In the play, players solve a rebus puzzle hidden by cards, which when removed reveal prizes in pairs. Players must remember where they've seen a particular prize and match it with its twin. Correct matches reveal parts of the overall puzzle. "Concentration" the television show and the game proved popular for years. This is the fourth edition of the original board game version. Concentration holds the distinction of the first board game to sell over a million copies in its first year. Most other games achieve that mark over a period of several years.