Some computer gamers prefer the feel of the keyboard and mouse over a gamepad. For others, however, the gamepad is their peripheral of choice for certain games. "Portal" supports the use of gamepads out of the box, and users can configure their gamepad for use by clicking a few of the game's options.
Plug the gamepad into the PC and run the "Portal" game application.
Click "Options" on the main screen and select the "Mouse" tab. Place a check mark next to the "Joystick" and "Joystick Look" options.
Click the "Keyboard" tab.
Double-click a command button on the keyboard and press the button on the gamepad you want that function assigned to. For example, if you want the spacebar's function to be assigned to the "A" button, double-click the spacebar and press the "A" button.
Repeat Step 4 for all of the keyboard functions you wish to be assigned to the controller. When you are done, click the "OK" button and use the gamepad to play the game.