Well, let’s look at this from the logic perspective. How does the BGE event layer determine the difference between a held click and a single click? In the Python api, there are different values for keyboard events, so you can simply check those, but, for logic bricks, it is a little more complex (only a little!). As I’ve explained recently, logic bricks have two states: positive and negative, and then there is triggering. Well, keyboard sensors and mouse sensors will easily allow you to fire “once” until released. This is because, when no pulse mode is enabled, the sensor only triggers the controller when it changes state. This only happens when it is first pressed and then released. So a simple setup of: Mouse -> And -> Actuator would suffice.