Defining Boundaries: Creating Credible Obstacles In Games
July 1, 2008 Page 1 of 5
['Why can't I jump over that wall?' In this intriguing design article, Sidhe's Griffiths (Gripshift) examines the usability-related issues - and solutions - for frustratingly invisible and unbreakable barriers in games.]
Throughout our everyday life, we come across barriers and boundaries which prohibit our movement. We instantly recognize them and know what we need to do when we come face to face. Some barriers we can easily circumvent; a door, for example, temporarily blocks our way until we open it and step through to the other side.
Games are the same. When we are in the game world we come across barriers which block our path and force us to turn around or open them up and step through to the other side. The problem with barriers in games is that they are sometimes not that distinctive.
What happens when we cannot tell the difference between a "friendly" barrier (one which we can interact with in some way) and one which is so unmovable that a nuclear missile wouldn't make a dent? More importantly, how does the player feel and what do they do to overcome this?
This article looks at the various techniques used by game developers to blockade our paths and, from a usability perspective, what it means for gamers.
Gaming technology is incredible. With new hardware advancements, developers are bringing us bigger and more exciting worlds. We often have the opportunity to roam for miles or to actually walk through entire cities, exploring seemingly every nook and cranny.
But what happens when there are areas in the game that developers don't want us to get to? Usually there is some kind of barrier that halts our progress or, alternately, an element of the story of the game which explains our inability to continue onward.
These boundaries are needed for a number of reasons, not least of all due to the fact that no matter how good our technology is, we simply cannot create a truly open-ended world. It is just not possible at the moment.
Boundaries also help us learn areas of the maps, because if everything was open to us at once then it would likely be simply too overwhelming to take in. By opening things up slowly to the player, we are introducing a gradual learning curve.
Another use of the barriers is to simply stop us from trying to go down certain areas of the game which simply don't exist. We can't have the players running everywhere because this means we have to create massive environments when it's simply not needed. So to overcome this we simply create barriers that halt the player's progression in certain areas.
The Answer: Human Computer Interaction
However, it is with these barriers and boundaries that a problem lies with game design usability. Unbeknown to players they actually rely heavily on two key principles in the field of Human Computer Interaction, or HCI: visibility and affordance.
In HCI texts, visibility and affordance applies to the controls that users can see. Donald Norman defines visibility as "Controls need to be visible which implies that there is good mapping between the controls and their affects. For example, the controls on a driver's dashboard have good visibility whilst video recorders have not." 1
Affordance is a technical term that refers to the properties of objects and how they can be used. A door "affords" opening. However, in HCI, what is more important is perceived affordance. This entails what the person thinks can be done with the object. Does the door suggest it should be pushed or pulled?
So how does this translate into games and game design specifically? Well for our discussion, we are looking at the game-world itself - the actual environment - and therefore we need to ensure that the players are always able to see their path through the game.
We should never have a situation whereby the player ends up at one point just sitting there, scratching their heads and unable to figure out where to go. This is not the same as a game which requires the player to figure out where to go.
1 - Preece, J. et al. Human-computer interaction. Addison-Wesley Publishing Company, Inc., MA, 1994
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