[In this first in a new series of articles, PhD researcher and game designer Lucas Blair uses academic research to formulate best practices for designing in-game achievements.]

Achievements are a hot topic in the gaming industry. Player feelings toward them range from obsession to indifference and designers seem equally torn over their use. Controversial or not, achievements appear to be here to stay, so designers need to learn to utilize them to their fullest potential. Achievements, if they are intended to have a positive effect on players, must be a forethought, and not an afterthought, during the game design process.

In many cases they are carelessly tacked on to a game after it is already close to completion. Unfortunately, the benefits of a carefully-crafted game mechanic can be undermined by attaching a poorly-designed achievement to it.

Alternatively, if achievements are designed in the same manner as other aspects of games, they can be used to improve the player's experience and the overall quality of a game.

There is an established body of scientific study covering a wide range of topics, which should guide the design of achievements. In this article series, I will be sharing a taxonomy of achievement design features created by deconstructing how achievements are currently used in games.

The goal of this exercise is to distill mechanisms of action out of achievement designs, which have been shown by research to affect performance, motivation, and attitudes.

This taxonomy, although intended to be comprehensive, is likely to be subject to debate and future revisions. For the time being however, I think it is a good jumping off point for a discussion that must be had if we are to ever effectively harness the potential of achievements.

In part one I will be covering the following concepts:

Measurement Achievements

Completion Achievements

Boring vs. Interesting Tasks

Achievement Difficulty

Goal Orientation

Measurement vs. Completion Achievements

The first branch in the taxonomy contrasts Measurement and Completion achievements, which describe two distinct conditions under which we reward players for their actions.

Measurement achievements are given to players for completing a task to a certain degree. Their performance can be measured against another player's performance, their own performance, or some standard set by game designers.

An example of this would be the star rating used in Angry Birds, which gives the player a number of stars based upon how well they beat the level. A measurement achievement can be likened to feedback, because it is evaluative in nature. The literature regarding the use of feedback in training and education indicates that feedback is beneficial to players because it allows them to reflect on their performance in relation to goals they have set for themselves.

This reflection increases the player's perception of competence, which in turn increases, their intrinsic motivation -- a term used to describe a task one finds inherently rewarding. That increase in perceived competence could also mediate the negative effects of other design decisions, like overusing rewards, which decrease intrinsic motivation.

On the other hand, completion achievements do not tell the player how well they've performed the task; instead they are offered as an award once a task is completed. Completion achievements can be split into two subcategories: performance contingent achievements and non-performance contingent achievements. Performance contingent achievements require skill to complete while non-performance contingent achievements are awarded for simply being present.

Performance contingent completion achievements, like those received for finishing a dungeon for the first time in World of Warcraft, can be better understood by reviewing what we know about the use of rewards as an extrinsic motivator. Some incentive programs have been shown to have a significant positive effect on task performance. However these types of rewards can decrease a player's sense of autonomy, especially when given in excess. This decreased sense of autonomy leads to lower intrinsic motivation.

Rewards also create an artificial ceiling for performance at the reward threshold. Once players have earned the reward, they are unlikely to continue on with the task that they were persuaded to do. For game developers this translates into the replay value of their game. Using rewards makes players less likely to take risks as they do not want to hurt their chances of being rewarded. This is especially relevant to rewards used in video games where designers wish to encourage creative and experimental play.

Non-performance contingent achievements, like earning a tabard or a pet for attending an in-game event, have no negative effect on intrinsic motivation. However these types of rewards do not have a performance measure, so players are unlikely to be interested in earning them unless they are paired with some sort of social reinforcement.

Best practice: Use measurement achievements instead of completion achievements to increase intrinsic motivation through feedback.