 Two contestants, one a returning champion, competed to solve a rebus concealed behind a 30-space board. Each contestant called out a pair of numbers on the board which contained the names of prizes, humorous joke prizes and WILD and action cards (the latter three explained later). No match passed control to the opponent, but a match gave whatever prize was printed on the card or allowed him to perform an action, revealed two pieces of the rebus (identifying a person, phrase, place, thing, etc.) and allowed him/her a chance to solve the rebus. WILD cards provided an automatic match, while TAKE cards allowed the contestant at that moment to snatch a prize his/her opponent might have in their possession. A FORFEIT card meant the player immediately had to give up one of the prizes he/she had in his possession. The joke prizes (things such as a banana peel, a button, etc.) actually served as insurance markers against opponents TAKE cards and the FORFEIT cards he/she might stumble upon. Only upon correctly solving the rebus does a player actually win what he/she claimed from the board; the loser forfeits all his gifts. Originally, there was no bonus game; later in the run came "The Envelope and its Mysterious Contents" (which hid cash amounts or a prize such as a car), and still later, "The Cash Wheel" which allowed a player to win up to $2,000 cash. Champions continued until either defeated or by winning 20 games; the top winners each season returned to play a "Tournament of Champions." During the original run of "Concentration," the show reportedly gave away 512 cars, 397 boats, 1,287 domestic and foreign trips and cruises, 12 trips around the world, 857 fur coats and numerous diamonds not to mention all the travel trailers, airplanes, swimming pools, furniture and countless other items (one history on the show reported the total prize giveaway at $10 million).