There are several reasons why the original Concentration is a game show classic. First, it's a very simple game that involves the home viewer. Second, unlike the big money quiz shows that died after the scandal the prizes weren't terribly high, except for a car. Third, there was plenty of drama as the contestants revealed portions of the rebus puzzle. Interesting note, the show's producer Norm Blumenthal created every rebus puzzled used on the air.
Let's not forget the hosts Hugh Downs and later Bob Clayton. Both were outstanding. For several months of 1969, Ed McMahon hosted the show but he wasn't accepted by loyal viewers, thus Clayton returned to front the show until it left the air in 1973 after the emergence of the Price is Right cut into the show's ratings and then new NBC Vice President of Daytime Lin Bolen wanted to get rid of the older, dated shows. Concentration was the last game show to use an organist.
As for the 70s revival, some things worked out well. The four head starts to begin each game, the addition of a bonus round and having both contestants play for the entire show. Jack Narz was very good as the new host, coming from Beat the Clock. But after a couple years, Goodson-Todman, who took over production from NBC decided to tamper with a successful show, speeding up the game with Free Looks and Bonus Numbers and making the rebuses easier. That's what caused the show to plummet in the ratings and end after five years.
