Understanding Puzzle Classifications: History, Methods, and Innovations

As it currently stands, there is no one universal or standardized way of classifying and identifying diverse kinds of mechanical puzzles that is accepted by everyone across the industry. People often describe puzzles by how they look, what material they are made from, or how many pieces they have, but these bits of information are not able to tell the whole story. This kind of description gets at the attributes of the puzzle and how it looks but it doesn’t necessarily classify the puzzle and categorize it compared to other puzzles that have similar methods or ideas.  There are broad terms like jigsaw puzzle, mechanical puzzle, or word puzzle that can differentiate certain ideas, but not with the specificity necessary to describe the difference between two puzzles like the Global Puzzle and Cube Puzzle. Suppose there are two puzzles made from the same material, both are 3D and have the same number of pieces, then what? This issue of classification has been around for centuries with the first real attempts at standardizing classifications coming from Professor Louis Hoffman’s book Puzzles Old and New in 1893.

Louis Hoffman

In his book Hoffman struggles with the existing nomenclature surrounding puzzles, as well as just how narrow the categories should be. More specific categories allow for a great number of different classifications, and therefore increased specificity. However, with more divisions it becomes harder to put a puzzle into one specific category, as often a puzzle will exhibit features of more than one category. In the end Hoffman devised 10 primary classes to divide all puzzles into, including mathematic, word, and logic puzzles. These 10 classes would go on to serve as inspiration for two of the most prevalent methods for classifying puzzles we see today.

Jerry Slocum

In the late 20^th century with puzzling and puzzle collecting on the rise, two new systems for classification came to be, first in 1987 from Jerry Slocum. Like Hoffman, Slocum devised 10 categories, however all 10 of Slocum’s categories describe different kinds of mechanical puzzles rather than including math and logic puzzles like Hoffman.  Within each category Slocum offers subsections to further differentiate each puzzle. Slocum dives deeper into subcategories that further describe mechanical puzzles in a way Hoffman couldn’t. It is also worth mentioning the changing landscape of the puzzle world Slocum dealt with in comparison to Hoffman. There was a much greater variety in puzzles, as well as a community developing around puzzles, with new ones coming out more often than ever. In the wake of the Rubik’s Cube and the craze that followed, it was more necessary than ever for someone to come up with the right jargon to keep up with the expanding world of puzzles. 

James Dalgety

Following Slocum, another method for comparing puzzles was invented by James Dalgety in order to describe the extensive Hordern-Dalgety puzzle collection. Dalgety changes a few things and adds a bit more detail, having 14 categories compared to Slocum and Hoffman’s 10, however there are still some significant similarities between the work of Slocum and Dalgety. Both systems have categories that point out the puzzle’s objective and process; the systems even share a few of the same categories. For example, both Dalgety and Slocum both have categories for sequential movement puzzles, interlocking puzzles, dexterity puzzles, folding puzzles, and even puzzle vessels. The exhaustive list of Dalgety’s 14 main classes (updated in 2017) are as follows:

• Dexterity Puzzles (DEX)
• Route-finding Puzzles (RTF)
• Tanglement Puzzles (TNG)
• Opening Puzzles (OPN)
• Interlocking Puzzles (INT)
• Jigsaw Puzzles (JIG)
• Assembly Puzzles (ASS)
• Pattern Puzzles (PAT)
• Folding and Hinged Puzzles (FOL)
• Sequential Movement Puzzles (SEQ)
• Jugs & Vessels (JUG)
• Other Types of Mechanical Puzzles and Objects (OTH)
• Ambiguous Pictures and Puzzling Objects (AMB)
• Non-Puzzle but related Ephemera (EPH)

Where the systems really separate from each other is in the detail and intricacy that Dalgety offers with his increased specificity. Beyond the additional four main classes, he also offers considerably more subcategories and subclassifications than Slocum. Under this system it is also advised to include a puzzle’s number of pieces and its dimensions (2D, 3D, etc.) when relevant. This helps to reduce the number of different classes, while still including all the necessary information. Each characteristic of a puzzle can be described under Dalgety in a way that was not possible with Slocum and Hoffman’s systems. Take a puzzle that would fall into Dalgety’s “Tanglement Puzzle” category for instance, the subcategories provided are able to describe the exact experience someone might have while attempting the puzzle without ever having to see it. Dalgety’s subcategories under Tanglement puzzles are:

• TNG-RIGI = Tanglement puzzle with rigid and/or semi-rigid parts
• TNG-R&F = Tanglement puzzle with both rigid and flexible parts
• TNG-FLEX = Tanglement puzzle with only flexible parts
• TNG-RING = Tanglement puzzle with finger rings.

These abbreviations and subcategories make the process of identifying, classifying, and talking about different puzzles considerably easier than in the past. Although increased specificity is a feature of Dalgety, Slocum and Hoffman made a point to avoid it, citing the fact that it would become difficult to classify puzzles that may appear to have qualities that would place it into multiple categories. To get around this pitfall, Dalgety adds a clause that outlines what to do in these cases. Stating that if a puzzle can possibly be placed in more than one category, it should be classified by its most significant one. With the most significant being decided by which class can be found closest to the solution. The following quote from Dalgety provides an example of a puzzle that could fit into multiple categories.