As John Miller has painstakingly documented, Martin Gardner's "Mathematical Games" column in Scientific American comprised 297 articles; Gardner also wrote 4 regular articles for SciAm. The contents of Gardner's column were reprinted (often with new, supplementary material) in a series of 15 books, sometimes half-jokingly referred to as "The Canon." The books are also available on CD-ROM.
I have a couple of questions on this topic.
Has all the content that originally appeared in SciAm been reprinted in the books and/or the CD-ROM? Or is there some material that appeared only in SciAm and that has not been reprinted? Unless I'm missing something, it's not so easy to determine the answer to this question from the pages I linked to above, because the columns were often retitled and repackaged when reprinted in the books.
Are new editions of all the books going to be re-issued? There is something called the The New Martin Gardner Mathematical Library, which supposedly was going to do this, but only four volumes have appeared so far, and nothing since 2014. It looks to me that the project may have died along with Gardner himself, who passed away in 2010. But maybe I am being too pessimistic, and Cambridge University Press and the MAA fully intend to complete the project?
As an aside, I want to mention that I found a very interesting review on Amazon by "D. Neff," which mentions some limitations of the CD-ROM, and indirectly suggests that the CD-ROM reproduces the books rather than the original pages from SciAm:
But the reason I dropped the rating to 4 for this particular edition is its sometimes haphazard quality of image scans. In the worst cases, the color or shading in the original figures is now black-and-white and of such high contrast that important distinctions are mostly or completely lost. For example, the reversi piece colors in figure 29 of "New Mathematical Diversions" are indistinguishable as are the four-color map areas (of all things!) in figure 43. Many figures show moire patterns from rescanning the original halftones. Yet other figures have been reproduced with much greater care, even in color. Some pages with landscape layout have been rotated for easier reading but others have not. In a few cases, the black-and-white photographs in my books have been replaced with much better color photos. Some books are missing a back cover scan.
The oddest example though, and somehow in keeping with the topic, is figure 109 in "Fractal Music". In my copy of the book, this is a reproduction of Magritte's "The Two Mysteries" and the caption says so. In this edition, it is a redrawn version and the caption now says it is "a caricature" of the Magritte work. At least 4 of the books appear to be affected by poor images and at least 6 of them appear to be fine.
I wrote to John Miller and Colm Mulcahy and they were able to answer my questions.
Essentially all the content of the SciAm articles has been reprinted in one book or another. But a detailed mapping of articles to book chapters does not seem to have been published anywhere. Dana Richards is apparently working on a biography of Martin Gardner, and perhaps it will include such a mapping.
The New Martin Gardner Mathematical Library project "withered on the vine for multiple reasons," according to Mulcahy. So we should not hold our breath for the next volume to appear.