In MGS4, players assume the role of Old Snake, utilizing stealth, CQC and traditional combat techniques. The overhead camera of earlier Metal Gear games has been replaced by a third person camera, with first-person view and over the shoulder cameras optional. A further addition to gameplay mechanics is the Psyche Meter. Psyche is decreased by non-lethal attacks, and is influenced by battlefield psychology. Stressors (including temperature extremes, foul smells and being hunted by the enemy increase Snake's stress gauge, eventually depleting his Psyche. Adverse effects include difficulty in aiming, more frequent back pain.