I am an EXTREME noob to the blender game engine and I’m making a 3rd-person-shooter. I was wondering how one would make the character turn according to the mouse movement. Thanks!
TUt1.blend (1.2 MB)
You need to add a mouselook script to empties and a camera. Also add a track-to to the player cube. I have a basic example here.
Using a mouselook script isn’t a mandatory requirement anymore, as of Blender Version 2.72, with the New Mouse Actuator that has the look function, you can easily add a Mouse Sensor with Mouse event on “Movement”, and then attach that to the Mouse Actuator that tracks the “X” Rotation. 
Here is an example from version 2.72:
From there you can adjust the Sensitivity to make the turn movement feel natural for you, this is also useful for looking in first person view as well while using it on a camera…