I just got a game controller for use with PC, I don't actually have a PS2 controller and I didn't expect them to cost like €15 in the shop.
I tried it on HL2. In options it has two options "use joystick" and "use joystick to look around". The buttons don't do anything, only the left analog stick. When I tick use joystick to look around i can look around with it, and when I tick the other i can move forward and look sideways. But the right analog stick doesn't work. The manual for the joypad just says u have to change the config in the game itself.
Blue I know that I'm not using it for online just HL2 to see what it like I've always played on consoles. Anyway that is not important.