So far, this book has placed little emphasis on the game machine's hardware, because the variety of processors, display screens, data storage, and audio devices makes it impossible to address the topic comprehensively. In the case of input devices, however, certain standards have evolved. It is critically important that you understand the capabilities, strengths, and weaknesses of the various devices because they constitute the means by which your player will actually project his commands into the game. Designing for them well makes the difference between seamless gameplay and a frustrating experience.
This section concentrates on the most common types of input devices for handheld, PC, and console games—the sorts normally shipped with the machine. It doesn't address extra-cost items such as flight control yokes, steering wheels, rudder
pedals, dance mats, fishing rods, bongo drums, cameras, and microphones. If you build a game that requires these items, you limit the size of your market to a specialist audience, and there isn't room to discuss such issues in a work on general game design. You should design for the default control devices shipped with a machine if at all possible. Only support extra-cost devices if using them significantly enhances the player's experience, or if you are intentionally designing a technology-driven game to exploit the device.
For most of their history, input devices for personal computers differed greatly from those of game consoles, so the two were best discussed separately. Console games never used analog joysticks; PC games never used D-pads. Now, both types of machines can use either, so we'll look at the various input devices independently of the platforms.