FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Some General Principles
The following general principles for user interface design apply to all games regardless of genre:
■ Be consistent. This applies to both aesthetic and functional issues; your game should be stylistically as well as operationally consistent. If you offer the same action in several different gameplay modes, assign that action to the same controller button or menu item in each mode. The names for things that appear in indicators, menus, and the main view should be identical in each location. Your use of color, capitalization, typeface, and layout should be consistent throughout related areas of the game.
■ Give good feedback. When the player interacts with the game, he expects the game to react—at least with an acknowledgment—immediately. When the player presses any screen button, the game should produce an audible response even if the button is inactive at the time. An active button's appearance should change either momentarily or permanently to acknowledge the player's click.
■ Remember that the player is the one in control. Players want to feel in charge of the game—at least in regard to control of their avatars. Don't seize control of the avatar and make him do something the player may not want. The player can accept random, uncontrollable events that you may want to create in the game world or as part of the behavior of nonplayer characters, but don't make the avatar do random things the user didn't ask him to do.
■ Limit the number of steps required to take an action. Set a maximum of three controller-button presses to initiate any special move unless you need combo moves for a fighting game (see Chapter 13, "Action Games"). The casual gamer's twitch ability tops out at about three presses. Similarly, don't require the player to go through menu after menu to find a commonly used command. (See "Depth versus Breadth" later in the chapter for further discussion.)
■ Permit easy reversal of actions. If a player makes a mistake, allow him to undo the action unless that would affect the game balance adversely. Puzzle games that involve manipulating items such as cards or tiles should keep an undo/redo list and let the player go backward and forward through it, though you can set a limit on how many moves backward and forward the game permits.
■ Minimize physical stress. Video games famously cause tired thumbs, and unfortunately, repetitive stress injuries from overused hands can seriously debilitate players. Assign common and rapid actions to the most easily accessible controller buttons. Not only do you reduce the chance of injuring your player, but you allow him to play longer and to enjoy it more.
■ Don't strain the player's short-term memory. Don't require the player to remember too many things at once; provide a way for him to look up information that he needs. Display information that he needs constantly in a permanent feedback element on the screen.
■ Group related screen-based controls and feedback mechanisms on the screen. That way, the player can take in the information he needs in a single glance rather than having to look all over the screen to gather the information to make a decision.
■ Provide shortcuts for experienced players. Once players become experienced with your game, they won't want to go through multiple layers of menus to find the command they need. Provide shortcut keys to perform the most commonly used actions from the game's menus, and include a key-reassignment feature. See the section "Allowing for Customization" at the end of the chapter.
