Whichever interaction model and camera model your game offers, you'll need to supply information that the player needs to know by using the visual elements discussed in this section.
The player's main view of the game world should be the largest element on the screen. You must decide whether the main view will appear in a window within the screen with other user interface elements around it, or whether the view will occupy the whole screen and the other user interface elements will appear on top of it. We'll look at these options next. (See also "Choosing a Screen Layout," earlier in the chapter.)
In a windowed view, the oldest and easiest design choice—the main view—takes up only part of the screen, with the rest of the screen showing panels displaying feedback and control mechanisms. You find this view most frequently in games with complicated user interfaces such as construction and management simulations, role-playing games, and strategy games, because they require so many on-screen controls (see Figure 15.4 for a typical example). Using a windowed view does not mean that feedback elements never obscure the main view, only that they need to do so less often because most of them are around the edges.
The windowed view really does make the player feel as if she's observing the game world through a window, so it harms immersion somewhat. It looks rather like a computer desktop user interface, and you see this approach more often in PC games than in console games. The loss of immersion matters less when the game requires a great deal of control over a complex internal economy and the player needs access to all those controls at all times.
If you want to create a greater sense of immersion than the windowed view offers, you can have the main view fill all or almost all of the screen and superimpose
graphical elements on it in overlays, small windows that appear and disappear in response to player commands. The most common type, the opaque overlay, entirely obscures everything behind it (see Figure 18.5 for an example). Opaque overlays carve a chunk out of the main view, but when they're gone the player can see more of the game world than in a windowed view, and she doesn't feel as if she's looking through a window.
Action games that don't need a lot of UI elements on the screen often use borderless opaque overlays—overlays that don't appear in a box. Compare the rather old-fashioned windowed view on the left side of Figure 13.2 with the borderless opaque overlays on the right side. The overlays obscure only a small part of the main view, which otherwise runs edge-to-edge.
Semitransparent overlays let the player see partially through them (see Figure 8.1 for an example). Semitransparent overlays feel less intrusive than opaque ones and work well for things such as instruments in the cockpit-removed view in a flight simulator. However, the bleed-through of graphic material from behind these overlays can confuse the information that the overlay presents. You can barely read the semitransparent overlay in the upper left corner of Figure 17.5 because it consists of light colors with a light sky behind. Be sure your overlay isn't too transparent.