Game controller

A game controller is an input device used to control a video game. A controller is typically connected to a video game console or a personal computer. A game controller can be a keyboard, mouse, gamepad, joystick, paddle, or any other device designed for gaming that can receive input. Special purpose devices, such as steering wheels for driving games and light guns for shooting games, may also exist for a platform. Some devices, such as keyboards and mice, are actually generic input devices and their use is not strictly limited to that of a game controller.

Gamepad

A gamepad, also known as a joypad, is a type of game controller held with both hands where the thumbs are used to provide input. Gamepads generally feature a set of action buttons handled with the right thumb and a direction controller handled with the left.
Most modern game controllers are a variation of a standard gamepad. Some common additions to the standard pad include shoulder buttons placed along the edges of the pad, centrally placed buttons labeled start, select, and mode, and an internal motor to provide force feedback.
Gamepads are the primary means of input on nearly all modern video game consoles. Gamepads are also available for personal computers, but few computer games support gamepads, preferring the more conventional keyboards and mice. However, most console emulators support gamepads.

Paddle

A paddle is a controller that features a round wheel and one or more fire buttons. The wheel is used to typically control movement of the player or an object along one axis of the video screen. Paddle controllers were the first analog controllers; they died out when "paddle and ball" type games fell out of favor.

Trackball

A trackball is basically an upside-down mouse that is manipulated with the palm of one's hand. It has the advantage of not requiring a lot of desktop space, and that it is as fast as one can roll the ball on it. This is faster than one can move a mouse due to space not being an issue. Notible uses of a Trackball as a gaming controller would be games such as Centipede and Golden Tee.

Joystick

This joystick is a computer peripheral that consists of a handheld stick that pivots about one end and transmits its angle in two or three dimensions to a computer. The joystick is often used for flight simulators. HOTAS controllers, which include extra hardware to simulate throttle and rudder controls are popular among fanatics of the genre.
This device can also be a home version of the kind used in the arcade, or for use on emulators. It features a shaft that has a sphere-like handle that is grasped, and one or more buttons for in game actions. Generally the layout has the joystick on the left, and the buttons on the right. There are instances when this is reversed, or the joystick is in the center with button on both sides.

Steering wheel

The steering wheel, essentially a larger version of a paddle, is used for racing simulators such as Gran Turismo, Forza Motorsport, and Live for Speed. Many are force feedback (see Force Feedback Wheel), designed to give the same feedback as you would driving a real car, but the realism of this depends on the game. They usually come with pedals to control the gas and brake. Shifting is taken care of with either paddles, a simple shifter which is moved forward or back to change gears, or a shifter which mimics that of real vehicles, which may use a clutch. Most wheels turn only 200 to 270 degrees lock-to-lock, but some models, such as the Logitech driving force pro, can turn 900 degrees, or 2.5 turns lock-to-lock.
The Namco JogCon paddle was available for the PlayStation game R4: Ridge Racer Type 4. Unlike "real" video game steering wheels, the JogCon was designed to fit in the player's hand. Its much smaller wheel (diameter roughly similar to a soda can's) resembles the jog-and-shuttle control wheel used on some VCRs.

Keyboard and mouse

The keyboard and mouse are typical input devices for a personal computer and are currently the main game controllers for computer games. Some video game consoles also have the ability to function with a keyboard and a mouse. The computer keyboard is modeled after the typewriter keyboard and was designed for the input of written text. A mouse is a handheld pointing device used in addition to the keyboard. For games, the keyboard typically controls movement of the character while the mouse is used to control the game camera or used for aiming.
The numeric keypad found on the keyboard is also used as a game controller and can be found on a number of separate devices, most notably early consoles, usually attached to a joystick or a paddle. The keypad is a small grid of keys with at least the digits 0-9.

Light gun

A light gun is a peripheral used to "shoot" targets on a screen. They usually roughly resemble firearms or ray guns. Their use is normally limited to rail shooter or shooting gallery games like those that came with the "Shooting Gallery" light gun. The first home console light gun was released on the Magnavox Odyssey; later on, Nintendo would include one standard on their Famicom and NES. Nintendo will release a light gun for its upcoming Wii console.

Touch Screen

A touch screen is an input device that allows the user to interact with the computer by touching the display screen. It was first used on a dedicated console with the Game.Com from Tiger. Nintendo popularised it for use in video games with the Nintendo DS; other systems including the Tapwave Zodiac as well as the vast majority of PDAs have also included this feature.
Modern touch screens use a thin, durable, transparent plastic sheet overlayed onto the glass screen. The location of a touch is calculated from the capacitance for the X and Y axes, which varies based upon where the sheet is touched.