The following is from the Wikipedia article about Pac-Man.
Pac-Man is an arcade game developed by Namco and licensed for distribution in the United States by Midway, first released in Japan on May 22, 1980. Immensely popular from its original release to the present day, Pac-Man is considered one of the classics of the medium, virtually synonymous with video games, and an icon of 1980s popular culture. Upon its release, the game—and, subsequently, Pac-Man derivatives—became a social phenomenon that sold a bevy of merchandise and also inspired, among other things, an animated television series and a top-ten hit single.
Sequels to Pac-Man
Identical to Pac-Man, except that Pac-Man is female.
Instead of eating dots, you eat keys! There are still ghosts though.
Pretty much the same as the original, with some colour changes.