Many computer video games involve a lot of rapid mouse clicking. But there are limits to how fast your finger can click and how long you can keep it up before your hand starts to ache. So I modified a mouse to add a rapid fire button to it. That way you can rapidly activate the clicking function by simply holding down one button.
To do this, I connected a 555 timer circuit to the terminals of the left mouse button. When the rapid fire button is pressed, the timer circuit sends a series of pulses to the controller that simulate the button being clicked. This circuit lets you click up to 800 times per minute. A similar circuit could even be used for console video game controllers.
See the complete series here.