clearstream
(He, Him)
Game designers followed in the footsteps of software engineers, who had themselves picked up the idea of design patterns from architects writing from at least the 1970s. There had been for at least a decade prior to Adams others proposing game design patterns including scholars such as Holopainen or Fabricatore, who had been writing papers alluding to them at that point for at least a decade.It is a textbook on game design, the one that (AFAIK) pioneered the idea of game patterns, and the book breaks down not only how to identify them but also how to construct them, and why and how they work as a design syntax that can be applied to every game ever made and ever will be made.
Adams was more the sort of writer who was able to communicate concepts others had developed to a wider audience, rather than said anything especially new. But perhaps I am underselling him as he articulately advocated a structured approach to game design.