You are presented withn the settings page which contains controls that allow you to change the values which are used to determine the nature of the runs.
There is a list of patterns that you can select with each one being slightly different. Speed, hidden time, switch direction time, processing loop time are all values that can be adjusted and saved before playing. Pattern 100 is used by for development and testing and has a fixed set of directions. The mouse will squeak and change direction and run faster if it is touched.