User interaction
There is no game without interaction with the user.
The standard way of doing this in GameMaker is to put actions
in mouse or keyboard events. But sometimes you need more control.
From within a piece of code you can check whether certain keys on
the keyboard are pressed and you can check for the position of the
mouse and whether its buttons are pressed. Normally you check these
aspects in the step event of some controller object and take
action accordingly.
Information on user interaction can be found in the following pages:
The Keyboard
The Mouse
The Joystick