Difficulty has often been oversimplified as a sliding scale between "easy" and "hard," which obscures the nuances that make every challenge unique. This is a significant problem for discussions on game design, where the role of difficulty is far more complex. Which challenges do players find engaging, and which turn them away? Why do some players find action games to be easy and strategy games to be hard, whereas for others, the opposite is true? Designers cannot properly answer these questions by relying on vague binaries like "easy" or "hard." Therefore, I propose a new taxonomy of difficulty, which classifies challenges into three distinct categories: comprehensive, executive, and strategic. Ideally, this taxonomy would not be limited to just games, but could also be applied to just about any activity.
The first category, comprehensive difficulty, describes the difficulty of understanding the core rules and objectives of a given task. For example, Rock-Paper-Scissors has a relatively low degree of comprehensive difficulty, as players only need to learn the game's titular three options. To contrast, there is a much higher degree of comprehensive difficulty in Pokémon, which requires players to memorize the various weaknesses, resistances, and immunities of eighteen different types. If the three questions that must be asked of any challenge are "what," "how," and "why," then comprehensive difficulty represents "what," and is often the first hurdle to be overcome. An example of an activity whose difficulty is almost wholly comprehensive would be learning a new language.
A chart demonstrating the complexity of Pokémon type effectiveness. Image from pokemondb.net.
As game designers, we should usually strive to reduce comprehensive difficulty as much as possible. This is because it is both the least satisfying type of difficulty to overcome, as well as the most frustrating to be stumped by. Ask yourself which would be more engaging: trying to come back from a strategically difficult situation in a board game, or studying that same game's comprehensively difficult rulebook? The rulebook example also leads us to another issue with comprehensive difficulty: Players often face the most comprehensive difficulty when learning a game for the first time, which makes them more likely to quit before they get invested. This issue is magnified for non-automated experiences such as board games and card games, because these games' rules only exist in terms of how the players understand them. In other words, if a player misunderstands a physical game, they will not merely fail its challenges, but are incapable of playing it properly at all.
Once you've understood the basics of a task, your next obstacle is often that of the second category: executive difficulty. Executive difficulty describes the levels of physical prowess (such as strength, dexterity, or reflexes) that are required to reliably perform an action. This category has the greatest degrees of variance between different tasks. For example, most sports possess extreme levels of executive difficulty at their highest levels, whereas games like chess possess almost none at all. Within the "three questions" framework of "what," "how," and "why," executive difficulty represents "how." An example of a task whose difficulty is almost wholly executive would be powerlifting.
Unlike comprehensive difficulty, the desired level of executive difficulty in a given game is not always so clear cut. Many action games use their high level of executive difficulty as their primary appeal, though different genres tend to hyperfocus on one aspect of execution while completely ignoring others. For example, most shooter games emphasize precise accuracy, whereas most fighting games emphasize precise timing, and neither generally requires physical strength. Alternatively, certain titles within these genres aim to provide executively easier alternatives. Examples include the fighting game Fantasy Strike, which utilizes simplified controls and a lenient input buffer, and the first person shooter Overwatch, which sports characters like Moira or Winston who rarely (if ever) need to aim. The existence of these titles and their fans proves that executive difficulty is not the sole appeal of action games, and that there are those who enjoy them despite that difficulty and not because of it.
A chart of the simple control scheme of Fantasy Strike by Sirlin Games, showing that it can be played effectively on any controller. Image from fantasystrike.com.
Part of why some players prefer to have less executive difficulty in their games is because it often distracts from strategic difficulty. For example, if a player perfectly predicts the opponent's actions in a fighting game, but then misinputs the move to best counter it, they might feel frustrated that the game's focus on execution "robbed" them of what was an otherwise strategically optimal choice. This is also why strategy games tend to eschew executive difficulty by default. There are once again exceptions, however, such as the real-time strategy game StarCraft: Brood War, whose executive difficulty surpasses that of most action games. Fans of Brood War feel that its strategic depth is enhanced by its executive difficulty, and so much like Fantasy Strike, Brood War is able to carve out a passionate niche for itself by defying the expectations of its genre.
Lastly, an important aspect of executive difficulty is that it can make certain games unplayable for individuals with physical disabilities. This is an extreme that does not apply to the other categories; While it is theoretically possible for just about anyone to eventually grasp a complex game, conditions such as arthritis can make rapid button presses painful and/or impossible to perform. Some executively difficult games can even cause physical injury, such as when the professional Super Smash Bros. Melee player Aziz "Hax$" Al-Yami developed severe joint pain in his wrists due to the game's emphasis on performing fast, repetitive motions during every second of a high level match. This is not to say that executively difficult games should not exist, but game designers have a responsibility to take these negative outcomes into account.
Once you understand a task's goals, as well as the physical abilities required to perform the task's actions, your final hurdle will be optimizing those actions to most effectively achieve those goals. This is strategic difficulty, the third and final category, and it is often the trickiest both to overcome and define. To demonstrate this, examine the difference between an intermediate Go player and a master. Both of them fully understand the game's rules, while also being capable of reliably moving their pieces to any desired spot on the board -- thus, they both have an equal mastery of Go's comprehensive and executive difficulty. However, the Go master will always win against the intermediate player, because they have a superior understanding of Go's strategic difficulty (i.e., the various tactics and divergent outcomes that will best lead them to victory). Go is a particularly important case subject for those interested in strategic difficulty, because despite being very simple to pick up and play, its strategic depths have still not been fully mastered even after thousands of years. Within the framework of "what," "how," and "why," strategic difficulty represents "why," and Go is one of the only examples of an activity whose difficulty is almost solely strategic.
Comprehensive difficulty and strategic difficulty are wholly separate concepts, despite the two often being conflated with one another. Comprehensive difficulty refers to the factual information that must be understood and memorized to fully grasp an activity, whereas strategic difficulty is concerned with how that information can or should be applied. This might seem like a pointless distinction, as most games with high comprehensive difficulty have high strategic difficulty as well, and vice versa. However, there are several cases where comprehensive and strategic difficulty vary wildly from each other, in terms of both their severity and their effects on the player. For example, in the trading card game Yu-Gi-Oh!, there are over ten thousand different cards in total, which loads a massive amount of comprehensive difficulty onto a new player hoping to read and understand them all. However, in high level competitive play, only an extremely small percentage of these cards are regularly used, and the prevailing strategies in which they are employed tend to be somewhat linear. This means that mastering the comprehensive difficulty of Yu-Gi-Oh! is harder than mastering its strategic difficulty by a significant margin; the former demands memorization of thousands of different cards, whereas the latter only requires an understanding of roughly three or four common strategies. Compare this to games like chess and Go, whose everlasting popularity can, in part, be attributed to their combination of low comprehensive difficulty with high strategic difficulty, making them easy to understand for beginners and fascinatingly deep for veterans.
An explanation of the strategically complex outcomes that can emerge from a single move in Go. Image from macworld.com.
A high degree of strategic difficulty can often be a desirable trait for a game to have. This is because, unlike comprehensive and executive difficulty, there is rarely a point at which a game's strategic difficulty has been definitively mastered, which allows players to continuously enjoy the feeling of self-improvement for long periods of time. When a game's strategy has been inarguably perfected, it is referred to as a "solved game," and is often abandoned by serious competitors as a result (a prime example of a solved game would be checkers). Additionally, strategic difficulty often contributes more to a game's "skill ceiling," which refers to the maximum level of proficiency that a game allows its player to reach, than its "skill floor," which is the minimum level of proficiency required for a player to play the game as intended. This is because strategic difficulty is rarely recognized by those who do not yet have a solid understanding of the rest of the game. For example, a master Go player can see an almost infinite amount of different strategic sequences extending from a single action, but a beginner will only notice the piece being placed on the board. By emphasizing strategic over comprehensive difficulty, the true complexity of a game can be effectively "hidden" from new players, preventing them from feeling overwhelmed before they become invested.
Strategic difficulty can also have some negative impacts as well, however. Many games achieve high levels of strategic difficulty by giving players a wide variety of different options, but if each of these options must be individually memorized and understood, then that tremendously inflates the game's comprehensive difficulty, which in turn inflates the game's skill floor. This is why games like Go, which are strategically difficult yet comprehensively easy, are so rare: It is incredibly challenging to design for strategic difficulty without also increasing comprehensive difficulty as well. Furthermore, strategic difficulty can also raise a game's skill floor all on its own, even without increasing the level of comprehensive difficulty. For example, in a strategically complex strategy game like StarCraft: Brood War, most new players will need a great deal of experience before they can understand when it is best to scout, expand, attack, or raise defenses, and until they have that ingrained understanding, they will fall so far beneath the skill floor that they might as well be playing a different game. Finally, due to the tendency that strategic difficulty has of raising the skill ceiling, it can be disadvantageous for multiplayer games that want their overall "skill gap" to remain low. These include party games like Mario Party, which are meant to be chaotic and exciting even when played by people of radically different skill levels, as well as games for young children such as Candy Land, whose low skill gaps ensure that parents do not defeat their children every time.
It is important to note that virtually every activity has some degree of difficulty in all categories. While the difficulty of learning to speak a foreign language is mostly comprehensive, it also includes the executive difficulty of speech itself, which is a challenge for people with speech impediments. Likewise, even if the difficulty of powerlifting is mostly executive, it still contains the strategic difficulty of knowing which stances and exercises are best suited for improving one's performance. However, by specifying the various nuances between comprehensive, executive, and strategic difficulty, game designers can more accurately analyze how each of their benefits and drawbacks can apply to different types of players. Games require an immense amount of forethought and knowledge to make, so it is only suitable that we use equally precise forms of language to describe them.