Usability In Mobile Games

Version 1.0 / 23 March 2004

Table of contents

• Usability And Fun - Best Friends In Mobile Games
• How to turn a good idea into a great game
• Where do I stand?
• Design and evaluate every step of the way

When you think of mobile games, you think of fun. But what does fun have to do with usability?

Fun is one of the main factors that differentiates game usability from usability in other applications. Mobile games are typically played for brief time periods, so there is no extra time to learn how to navigate inside the game. Playing should be as intuitive as possible and the challenge should be in the game play, not in the interaction with the game user interface.

Usability provides the framework and tools for playability, which is a quality every game must have in order to survive. Playability is defined as the degree to which a game is both fun to play and usable, with an emphasis on the interaction style - the quality of game play.

It has been said that an individual game lives or dies by its interface. If usability problems get in the way of intense game playing, the game probably will not be played again.

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How to turn a good idea into a great game

Navigating in the waves of a game experience When playing a game, users should experience the game world, and in order to do that the game navigation structure should support the experience. Use of high-level UI components should be avoided. Game menus should look and feel like the game. If high-level UI components are used, they should support the game experience seamlessly.

Figure 1: Three different game menu implementations

Figure 1 displays three different implementations of the same game. In the first example, both the game menu and the game are implemented with custom graphics in full-screen mode. Here, the game experience is not disturbed by phone graphics. This kind of seamless experience should be the goal when designing game navigation structure.

Should there be an interruption Mobile games are played in a context where interruptions often occur: somebody might call or send an SMS message, or the player might need to pause the game to buy a bus ticket. Therefore, the game design should support saving and pausing.

There are novice and expert users among mobile gamers. Novice users often need more help than expert users. Help should be available if needed, easy to access and quick to read. These design principles are useful:

• Make help text brief. Concentrate on the controls in the help text (Figure 2).
• Provide in-game help (Figure 3). Display short text on the screen to explain new items, characters, and situations in the game. Provide a setting to disable in-game help, too.

Figure 3: In-game help in Yo-Yo Fighter by Sumea is activated when user touches help icon

Almost like the real world The user has expectations of how his/her surrounding environment works. The game world should match that model. Movement and moving objects in the game world should be intuitive, and obstacles and possibilities should be easy to detect.

• The game should function like the real world, to the degree that it's possible. For example, when characters are jumping or throwing objects, the flight path should be predictable
• There must be no invisible barriers that the player cannot pass or holes that s/he cannot reach (Figure 4).
• Do not kill the user/game without letting the user do something about it.
• Match functionality and outlook. Things should do what they seem like they are supposed to do, and look appropriate to the function they perform in the game.
• Do not force the player to learn new things if s/he can utilize his/her prior knowledge. Implement a realistic physics model.

	Before applying the guideline The game has an invisible barrier to the right of the spaceship - the player cannot go right, although there is nothing visible preventing him.
	After applying the guideline The new version does not contain such barriers. Note the little information circle where a player can get hints on how to play the game.

Figure 4: Invisible barriers were removed after user testing to make game world match real world (example presented in Developer Platform 1.0 for Series 40: Usability Guidelines for J2ME™ Games)

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Where do I stand?

The user must always understand his/her current status and the status of other players. Critical information about the game character's health, weaponry, money, etc., must be conveyed to the user clearly, without risk of misinterpretation.

• Determine the most important information for players and display it clearly on the screen, making sure there is not too much information - one or two status indicators are plenty for most games. If this is not sufficient, the design may need to be refined to allow a simpler interface.
• In multiplayer games, players must be able to identify both their own and the other players’ status at all times. For example, in racing games the player should be able to follow where others are on a map, and in puzzle games the player should be able to see the scores of the other players. Players can’t imagine a good action game if they can’t at least select the opponent and view his/her status. An even better solution is to show the status on the small screen all the time.

Go easy on the sounds Mobile games are often played in public places with other people around. Music and sounds might be a good addition to the game experience, but a great disturbance for others. Therefore:

• Provide a silent start-up, rather than one with music.
• Provide a sound menu in the game to make sure the player can deactivate or activate sounds.

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Design and evaluate every step of the way

Usability guidelines are handy and useful design tools. In order to guarantee good usability, evaluation should be a fundamental part of the development process. Even though mobile game development processes are very short, there are techniques and methods, such as expert evaluation and group testing, which have proven to be useful for mobile game developers. Usability is not the only factor that produces good games and gaming experiences, but without it no games could ever be played.

Related More games guidelines can be found in the Usability pages of Forum Nokia. Those useful guidelines focus on game play. New mobile game usability guidelines focusing on multiplayer games will be available within the next few days. In multiplayer games, other players provide the main challenge. There are numerous ways that a game design can support that scenario.

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