Sensors are the logic bricks that cause the logic to do anything. Sensors give an output when something happens, e.g. a trigger event such as a collision between two objects, a key pressed on the keyboard, or a timer for a timed event going off. When a sensor is triggered, a positive pulse is sent to all controllers that are linked to it.

The logic blocks for all types of sensor may be constructed and changed using the Logic Editor details of this process are given in the Sensor Editing page.