I've been reading Emotional Design by Don Norman. This book is half a philosophical discussion of product design and half speculation about future technology. But the parts I found the most useful were the descriptions of how emotions result from and guide a user's interaction with a product. In this post, I am distilling out those emotional chain reactions (my term) and applying them to board game design. [NB: I'm not an expert on emotion and this information is not meant to be used outside of game design.]
There are two main chains of emotions described in the book (although not as explicitly as I have depicted them here): the anxiety chain and the happiness chain (again, my own terms). The anxiety chain starts either with frustration or confusion. Frustration can result from struggling to learn or to execute actions or from a sense of danger (such as the danger of losing). This type of frustration can be used to build tension in a gameplay arc. Frustration can also result from feeling a lack of control. Feeling a lack of control can lead to a lack of trust in the design. Frustration can lead to anxiety. Confusion should be avoided in game design, but will lead to a similar state of anxiety as frustration does. Anxiety causes increased concentration on the details of a problem. Anxiety produces focus. Focus is useful in heavy strategy games. High levels of anxiety can produce the desire for escape. These sensations can create fear. Fear, if overcome (or if the threat is overcome), produces pride and a sense of achievement. Players also feel pride in overcoming obstacles and refining their strategy. However, high anxiety coupled with lack of control will lead to anger.
There are some important things to note about anxiety chains. Too much frustration will drive away players. On the other hand, shared experience of these "negative" emotions can lead to increased social bonding—a positive outcome. Players in a state of anxiety will be less open to interruptions, as such prevent the concentration created by their anxiety. Humans are less able to learn while in a state of anxiety. Any new rules must be presented clearly and be easily referred back to. Anxiety chains seem best suited to intellect-challenging designs or horror-themed games.
Emotional Design helpfully includes a list of things that can produce feelings that belong in the anxiety chain: heights; sudden, unexpected loud sounds or bright lights; looming objects; extreme hot or cold; darkness; empty, flat terrain; crowded, dense terrain; crowds of people; rotting smells; decaying foods; bitter tastes; sharp objects; harsh, abrupt sounds; grating, discordant sounds; misshapen human bodies; snakes and spiders; bodily fluids and vomit. I don't think these are needed to produce tension in a euro game, but in horror games they fit right in. You could also use only one or two elements—a few sharp objects in an eerily empty terrain, for instance—to shift the tone of a location to a tenser, more anxious feel.
The happiness chain starts with some combination of attraction, fun, and/or pleasure. Attraction is our response to aesthetics, in this case specifically non-utilitarian pleasure. (Much of aesthetics, fun, and pleasure overlap, so I attempted to emphasize the least overlapping, most relevant aspects.) Of the eight types of fun, I feel that fantasy, narrative, discovery, and expression best fit as a description of "fun" within the happiness chain (again, due to overlap). However, the only type of fun I would leave out of the chain is challenge, as it clearly belongs on the anxiety chain. Don Norman cites Patrick Jordan's study, Designing Pleasurable Products, to explain the four types of pleasure. Of those four, two are useful here: physio-pleasure and socio-pleasure. Simply put, pleasure arises from our physical senses and our social interactions. Clearly, these two elements could be lumped into "fun," but I will leave fun and pleasure separate as Mr. Norman did. Attraction, fun, and pleasure lead to positive feelings of enjoyment, which he terms happiness. Players in such a positive state will be more inclined to curiosity and creativity. Problem solving and learning are also more likely outcomes. Positive emotions such as in happiness chains produce better conditions for brain storming than negative emotions.
The happiness chain is not very linear. It resembles a method of brain-storming, which is fitting since the style of thinking promoted by this chain is well suited to brain-storming.
Happiness chains allow players to be more open to interruptions and more receptive to new ideas. However, happiness chains produce less concentration and focus as a result. Happiness chains are well suited for party games, games with high randomness, and games that require a certain amount of flexible thinking during gameplay.
Dan Norman also supplies us with a list of things that produce the positive emotions found in the happiness chain: warm, comfortably lit places; temperate climate; sweet tastes and smells; bright, highly saturated hues; soothing sounds; simple melodies and rhythms; harmonious music and sounds; caresses; smiling faces; rhythmic beats; 'attractive' people; symmetrical objects; rounded, smooth objects; 'sensuous' feelings, sounds, and shapes. Kids' and family games tend to showcase art emblematic of this list. These images produce feelings of peace and safety. You probably don't want to visually design your combat game around this list, although Root made a high-conflict, high-strategy game more approachable by using friendly looking art. Just be aware of what emotions your design choices will create.
In addition to the two main chains, Emotional Design mentions how to create other emotions or what those emotions in turn inspire. Joy (a subset of happiness, presumably) creates an urge to play. Interest (perhaps another term for curiosity) creates a desire to explore. Hope is created by the expectation of a positive result. (Anxiety can also be characterized by the expectation of a negative outcome.) Relief occurs when an expected negative outcome doesn't happen. Disappointment results from an expected positive outcome not occurring. Remorse occurs when you perceive a negative outcome as your fault. Reproach occurs when a negative outcome is perceived as someone else's fault. Gratification is the result of a positive outcome that you are responsible for. Admiration results when a positive outcome occurs because of someone else. Surprise occurs when a situation does not unfold as anticipated and results in the need to reassess plans. Trust requires reliance, confidence, and integrity. Trust is required for cooperation. Embarrassment reflects your individual sense of appropriateness of behavior.
Hopefully, this breakdown provides useful tools for designing emotions (intentionally) into games as well as diagnosing why some emotions feel out of place in certain games. The anxiety chain can additionally be used to figure out why playtesters are frustrated at various times while playing a prototype. Understanding the 'logic' behind emotions is a powerful tool in a designer's toolbox.