In 1982 pac man was a phenomenon. It was the most popular arcade game by far, and hence generated a huge demand for versions to play at home. In the 80s enthusiasts in their bedrooms were the generators of much of the content, and to them, copyright, corporate branding and legal protection were unknowns – hence we saw numerous pac-man clones, some more accurate than others. However, even in 1982 it was apparent that video-gaming was to be a highly lucrative market, and as a result, a more ‘grown-up’ heavyweight approach to the scene emerged.
This op-ed piece from Computer and Video Games puts it into some perspective.