The user interface (UI) creates the player's experience, making the game visible, audible, and playable. It has an enormous effect on whether the player perceives the game as satisfying or disappointing, elegant or graceless, fun or frustrating.
In this chapter, you'll learn the general principles of user interface design and a process for designing your interface, along with some ideas about how to manage its complexity. We'll then look at two key concepts related to game interfaces: interaction models and camera models. After that we'll delve into specifics, examining some of the most widely used visual and audio elements in video game UI and analyzing the functionality of various types of input devices. Because the overwhelming majority of video games include some notion of moving characters or vehicles around the game world, we'll consider a variety of navigation mechanisms as they are implemented in different camera models and with different input devices. The chapter concludes with a few observations on how to make your game customizable.
What works is better than what looks good. The looks good can change, but what works, works.
—Ray Kaiser Eames, Designer and Architect
As you saw in Figure 2.1, the UI lies between the player and the internals of the game. The UI knows all about any supported input and output hardware. It translates the player's input—the button-presses (or other actions) in the real world— into actions in the game world according to the interaction model (see Chapter 1, "Games and Video Games"), passing on those actions to the core mechanics, and it presents the internal data that the player needs in each situation in visible and audible forms.
This chapter refers to the outputs as the visual elements and audio elements of the user interface and to the inputs as the control elements. When the game gives important information to the player about his activities, the state of the game world, or the state of his avatar (such as the amount of health or money he has), we say that it gives feedback to the player—that is, it informs him of the effects of his actions. The visual and audio elements of the user interface that provide this information are called feedback elements.
Any discussion of user interface design runs into a chicken-and-egg problem: You can't learn how to design a good UI without already knowing the names of common visual elements such as power bars and gauges, and this chapter can't introduce the common visual elements without making references to how they're used. So, to address the most critical information first, we'll start with the principles of interface design. If you encounter a reference to an interface element you've never heard of, see the section "Visual Elements" later in the chapter for an explanation.
Dozens, perhaps hundreds, of published books address user interface design, and this chapter does not try to duplicate all that material. The following sections concentrate specifically on user interfaces for games, how they interact with the game's mechanics, and how they create the entertainment experience for the player. To read more about user interfaces in general, see The Elements of User Experience by Jesse James Garrett (Garrett, 2003).