The Milton Bradley Company introduced the first commercial version of Concentration in 1958 and subsequently released 24 editions of the game until 1982. (Owing to common superstition, these releases were numbered 1-12 and 14-25, skipping 13.) It was tied with Password as the most prolific of Milton Bradley's home versions of popular game shows, and was produced well after the Jack Narz era ended in 1978. Pressman Games also published two editions of the Classic Concentration home game in 1988. More recently, Endless Games has released two versions of Concentration since 1998, one with a red viewer window & one with a clear window. The Endless versions were modeled similar to the Classic Concentration home games with a 25-square board and rebuses designed by Steve Ryan, who created puzzles