In addition, it is also nice if the keys could be redefined but that is not necessary.
The standard CPC can support 3 joystick buttonsper joystick, though many CPC joysticks only have 1 button.
The CPC+ and GX4000 only support 2 buttonsper joystick, and the included Amstrad joypads have 2 buttons.
There are some common keyboard configurations used: