Vendetta is played with the joystick. In addition, the SPACE key is used to
select your weapon (fists, knife, machine gun etc.), and the RETURN key is used
to select an object. To use an object, you must select it and press the fire
button on the joystick. If you want to use the object again, you must select it
again using the RETURN key.

To kill the guards and use your weapon, press the fire button. To search for
objects, press the Fire button and move the joystick in any direction at the
same time. You must be in exactly the right position to search for objects and
to kill guards, so try different positions!