I have used force sensors to take input from rocks, put them underneath every rock.

For mouse button 1, mouse button 2 and middle mouse button I have used stick with vibration sensor and 2 buttons,
– no button pressed and you smash the stick then MB1(left mouse button) will be activated
– first button pressed and you smash the stick then Middle mouse button will be activated
– second button pressed and you smash the stick then MB2(right mouse button) will be activated