A formal definition to describe a pattern would be a reoccurring part(s) that directly affect game play.
Game design is more difficult to define than most other design subjects because of the simple reason that games are artificial objects rather than natural ones. They are also entirely designed by humans which makes the process of creating a game with immersive and exciting game play difficult to understand. Designing interaction is they key to creating game play. No other medium provides interaction like videogames. If people are able to interact with a game successfully then game play is born. Most aspects of creating games are predictable, using the same engines along with the same formalized modeling and textures techniques. However, that is just the surface of game design and we explore the subject more it becomes clear that there are a lot of elements to a game that are impossible to anticipate.
As a core rule, if you think of game design as interaction design, the process becomes much clearer, the interaction being the usability between humans and computers. The three main areas to identify when looking at patterns in game design are the creation of patterns from problems, following on patterns and editing patterns. When creating a pattern from a problem the designer can identify a core issue that is wrong with the design, however this technique used on its own only removes the unwanted effect and does not tackle what the design is trying to achieve. Using following on patterns can be applied to multiple patterns when a certain pattern does not work when confined on its own. Editing Patterns can be useful when a designer wishes to introduce, remove or modifying existing game play however the designer has to be careful when using this tool because if a pattern is edited too much then it may completely alter the feel of the game play.
If so many potential problems can be caused by the three main areas of pattern design why do designers still use these techniques? The reason we use these tools is because patterns in design do offer a good model for how to structure knowledge about game play that can be used in the design and analysis stages. The key is not to isolate elements but bring together many different techniques in order to get the desired effect.
Semi-Formal descriptions are what patterns rely on for a general description of a specific area of game play without using quantitative measures. This could include anything from open doors, jumping, navigating levels, anything that is directly affecting the game play of the game is given a semi-formal description. The reason why designers do not use quantitative measures is because they are too precise for solving ill-defined problems of design. The presence or effect of design cannot be measured and for this reason it is an impossible technique to implement. However patterns do have a structure and relationships that can be identified. This therefore leads to patterns a semi-formalised concept to be applied to their intended use.
After looking at semi-formal descriptions the designers then move onto interrelated descriptions which means that all the patterns can somehow all be related in someway. Although it is common that some relationships are more popular than others depending on the game type. The 5 main relationship types that emerge, the first one being instantiates which applies to a scenario has an existing pattern and then causes the next to be present after that. The second are modulate patterns which is when the first pattern affects aspects of the second pattern but does not have to affect the entire pattern. The third relationship type is ‘instantiated by’ which is when the pattern can be instantiated by ensuring the presence of the related pattern. The fourth type is ‘modulated by’ which applies when an additional pattern can tune a patterns affect on game play. And finally, the fifth relationship type is a ‘potentially conflicting with pattern’ which can make presence of other patterns impossible. Although there are 5 different relationship types this does not mean that it has to be an either or situation in which only one relationship can apply to a certain type of game, sometimes multiple relationships can exist in games because of how the game is intended to be played is not necessarily the way a player plays the game and other unintended relationships may form through this type of play.
Which leads us on to intentional or emergent presence. This is when a game design pattern may be found in game play that was either intended by the designer or an unplanned consequence of the configuration of the game. The unintentional patterns in games are often classed in a hierarchy at the highest level meaning that the patterns are harder to design. This is common sense if the player has unintentionally found a pattern as the designer did not plan this design whereas a lower level would include a core set of rules the designer has laid down.