The precursor to this book, The Encyclopedia of Chess Variants, lists 1450 different games, all based on chess. It was published in 1994, but is now out of print and hard to find. Thus I was overjoyed to learn that a second edition (with a slightly different title, The Classified Encyclopedia of Chess Variants) came out in 2007.
Since it's not currently available in North America, I had to order it through Amazon in the UK. By a strange coincidence it arrived the same day the local library called. Months earlier I had requested the first edition through interlibrary loans. Suddenly I had both books in hand and was eager to compare them.
The most obvious difference is that the second edition has been completely reorganized. Entries are no longer in alphabetical order; they are grouped by type, which explains the word "Classified" in the title. The table of contents runs to eight pages, and includes entries such as:
New pieces
Mutation games
Games for three
Transporting and teleporting
Unorthodox ways of capturing
Boards based on hexagons
Cylindrical, toroidal and spherical boards
If you're looking for a particular game and know its name, you must resort to the index at the back, which uses a decimal numbering system instead of page numbers. For example, the entry for Octopus Chess is 35.4, which means it is found in section 4 of chapter 35. The method is logical but a little cumbersome.
A somewhat larger failing is the sparsity of illustrations, which makes the book less useful than the first edition. Without an illustration, visualizing an unusual game board (such as Three-Player HyperChess, shown here) can be tough.
The reason for the paucity of illustrations is a sad one. The author passed away in 2005 while still working on the second edition. The task was completed by John Beasley, but the original artwork could not be found.
In sum, the first edition is easier to use and more fun to page through. But does that mean I regret purchasing the second edition? Indeed, not. I am delighted to own it and salute John Beasley for helping to keep this unusual and valuable publication in print.
[August 2015 note: The entire book is online at John Beasley's website.]
More
Pritchard's Popular Chess Variants describes 20 of the most popular games, and in greater detail than his encyclopedia. It's available in North America. There's also lots of info on the Web:
Chess Variant Pages
British Chess Variants Society
Play Chess Variants