Keeping Everything Under Control

In a console- or PC-based game, controls comprise supporting keyboard, mouse, or joystick/gamepad. In an iOS game, you have access to two main forms of control: the touchscreen and the accelerometer.

Because in Raiders the player moves only across the bottom of the screen, you could exclusively use the accelerometer to tilt the player to the left and right. The advantage of doing so is that you don’t need to draw onscreen controls that take up valuable onscreen space. The disadvantage is that you must ensure that the tilt performance isn’t too sensitive—so the player flies off the edge of the screen with the slightest bump—or too sluggish—so the player has to tilt the device so extremely that he can no longer see the game screen.