I'm lost. An NPC just told me what I was supposed to do, but I was distracted by the loot in the middle of the room and the Giant Spiders coming at me from all directions. It doesn't help that that I can't access the NPC anymore, or that all of the rooms in this dungeon are the same shape and color. Lost. I have no idea where to go or how I'm supposed to get there. Fifteen minutes pass before I find the puzzle I need to complete. But now I have no idea which of the 20 quest items in my inventory I should use to solve it. After a while, I give up in frustration.
Flow breaks down when a player doesn't know what their goals are, how they're expected to accomplish them, or which new game techniques they're supposed to use to solve a puzzle. When this happens, gamers disengage and are more likely to stop playing.
We have limits on our information processing and attentional capabilities. Not all of the information coming from the screen or out of the speakers gets processed. While we are capable of handling a lot of visual and auditory information at one time, we do have limitations.
Critical processing restrictions occur when our attention is divided. This can happen when task-relevant information is presented too quickly or when multiple sources of stimulation are competing for our attention. In either case, task performance can drop dramatically. When this happens, people become anxious about accomplishing their goals, thus inhibiting Flow.
Another aspect of information processing that can be overlooked is the congruency between directions and task. People are best able to understand and apply relevant information to a task when there is congruency between the task and the information/instructions.
Our ability to problem solve and make decisions is directly affected by information processing and attentional issues. When there are breakdowns in information processing, comprehension of task goals and rules also suffers. If people do not understand the nature of a problem, they can become frustrated attempting to solve it. These peaks in frustration decrease Flow and also affect problem-solving techniques.
When overwhelmed with too much stimulation, people will often revert to methods of problem solving that have worked in the past. These reversions may or may not be what the developers had in mind.
Concrete goals with manageable rules are achievable. The act of achieving goals is rewarding and reinforces actions that allow individuals to continue completing goals. Whether it's leveling your character or earning points for head-shots, the very act of accomplishing something reinforces your desire to keep accomplishing. This goal-achievement-reward cycle can keep gamers glued to a game and facilitates Flow states.
If designers are able to take into account the psychological factors mentioned above, they can easily address issues with rules and goals.
If players are readily able to accomplish goals, they are more likely to continue playing. Though, as previously mentioned, there must be a balance between the player's skill and the difficulty of task.
I know I'm supposed to swipe in the opposite direction of the Fiend's attack. This should parry his attack, opening him up for my own counter. But I just can't do it. Whether it is lack of reflexes, or the fact that I just started playing the game, I'm hopelessly inept. I'm also seriously frustrated.
Understanding the limits of player ability and cultivating player skill is of critical importance. If players are unable to accomplish goals -- even if goals and rules are clear -- then they will find their gaming experience dissatisfying.
Even beyond the obvious answer -- "Because players will stop playing!" -- there exist many psychologically based considerations worth enumerating. Here are a couple of them:
Stress and performance affect Flow. If a player isn't skilled or capable enough to accomplish game-based goals, they may experience stress-provoking drops in performance. This kills Flow states and drives down the overall enjoyment of the gaming experience.
Goal difficulty and player perseverance. As goals become increasingly difficult to accomplish (in relation to player skill), commitment to accomplishing these goals diminishes. If this happens, a gamer is very likely to simply stop playing.
Figure 2: Performance as a function of Arousal/Stress. Adapted from Yerkes & Dodson, 1908, and Hanin, 2007.
Each gamer has a unique performance-stress curve (see Figure 2). This means that for some people +7 stress (an arbitrary value) causes them to operate at their highest level of performance, but for a different person +7 stress results in them failing spectacularly.
This also means that coarse gradations of game difficulty (e.g., Easy, Normal, Hard) may not lead to an optimal experience for many gamers.
Game developers could include AI that are able to dynamically adjust the in-game conditions affecting difficulty, thus positively affecting player performance (e.g., the AI Director in the Left4Dead series).
One critical consideration for such an AI is the relationship between performance and enjoyment. Some players may perform extremely well when dynamic difficulty is increased; however, they may not enjoy being under such high levels of challenge. In this case, they may feel anxiety (e.g., Fig. 1). Game developers could identify this by marking players who have high performance and high quit-rates (i.e. the player quits in response to changes in difficulty, but their performance remains steady).
Another consideration is how these AI handle difficulty for multiplayer teams (e.g., four players in a Left4Dead 2 campaign). In these cases it is important to recognize that dynamic changes to difficulty may affect players of varying ability in different ways. Thus, it is crucial to determine how to optimally change difficulty without ruining the game for very good or very bad players on the same team.
Certain game-specific skills must be slowly taught to players. If a game does not leverage skills commonly used in gaming (e.g., typical FPS controls and aiming), players must be gradually taught the new game-specific skills. Because of previously mentioned information processing restrictions, this sort of in-game training should occur in a relatively subdued environment.