An input device is a control that is (with video games) traditionally a piece of hardware used to gather input from the user. This includes such items as joysticks, joypads, game paddles, fishing controllers, light guns, pushbuttons, pedals, electrosensitive mats, mice, and other devices through which players send messages to the game software.
Input devices differ from input methods in that the devices translate human action (typically motion) into electronic messages which are then accepted and interpreted by the game software. At both levels there is translation going on to enable the user to control or influence the game. Input devices constitute how user input gets translated into electronic signals, input methods the manner in which the game software interprets those electronic messages.
As noted previously, most input devices focus on translating human motion into electronic messages. Devices like joysticks, game paddles, joypads and pushbuttons are common examples. There are also input devices that focus on audio and visual input. For example, some games use speech recognition interfaces to allow voice commands, such as in Lifeline [Konami, 2004], Seaman [Saito, 2000] or sing-along tone matching like in Karaoke Revolution [Randall, 1993]. Examples of current visual inputs include EyeToy: Play [SCEE Studio Soho, 2003], which uses a video camera to track motion within the camera's field of view and "light gun" games like Duck Hunt [Nintendo, 1985] or Time Crisis [Namco, 1996] which optically sense where the gun is pointing on the game screen. Note that like haptic inputs, data gathered by current visual inputs is largely reflective of player movement. EyeToy games are designed to respond to players' movements within the video frame. Games using a light gun essentially measure where the gun is pointing on the game's screen. In some cases, designers opt to replace the light gun technology with a joystick system that provides the same degree of freedom in its input, such as in Silent Scope [Konami, 1999].
We've chosen to examine input devices as sets of channels and interpretations. That is, the device sends a signal over a channel which is received and interpreted so it can be understood by a game's input methods. In this sense, what we're calling input devices is mostly hardware, but also covers software necessary to making the use of input hardware possible. (The routines that receive the raw input streams from the input hardware and make them useful to a game's input method.) The complexity of such interpretive code varies. In the case of games using speech recognition, very complex software goes about parsing and translating the raw audio stream into words that the game then matches to its set of available commands (typically a flat command menu). For games which use an analog joystick to provide direct control over the player character's representation within the game (like a platformer or first person shooter), there is less complicated software at work, the game interpreting the numeric input from the joystick into walking or running in a specific direction.1
For certain devices, these interpretations may take different of input devices and translate them into similar interpreted signals. This would allow for substituting input devices for one another, such as using a joystick in place of a mouse or vice-versa. The game's input methods then receive the interpreted messages from the joystick or mouse and use those messages to move the player's character, navigate a set of menus, etc.
It's useful to note that input devices are polled by their interpretive software over time, the "poller" checking the device's state at a certain rate (n times per second). This rate can vary according to the needs of the device. For example, haptic devices that offer resistance to simulate physical contact with game objects require a higher sampling rate than haptic outputs that don't provide such specialized feedback.
The current list of input devices below is far from exhaustive, but gives the initial idea for how we're describing input devices.
- Analog Pushbutton
- Digital Pushbutton
- Direction Pad
- Fourway Joystick
- Rotary Paddle Control
- Thruster (two-way) Joystick
- Touch-Sensitive Screen
Konami, developer (1999). Silent Scope. Konami Corporation, arcade edition.
Konami, developer (2004). Lifeline: Voice Action Adventure. Konami Corporation, playstation 2 edition.
Namco, developer (1996). Time Crisis. Namco, arcade edition.
Nintendo, developer (1985). Duck Hunt. Nintendo, nintendo entertainment system edition.
Randall, J. (2003). Karaoke Revolution. Konami of America, Inc., playstation 2 edition.
Saito, Y. (2000). Seaman. Sega, dreamcast edition.
SCEE Studio Soho, developer (2003). EyeToy: Play. Sony Computer Entertainment Europe, playstation 2 edition.