Metal Gear Solid 4

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 The overhead camera of earlier Metal Gear games has been replaced by a third person camera, with first-person view and over the shoulder cameras optional.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 and the possibility of Snake passing out upon receiving damage. Among the available methods of restoring Psyche are eating, drinking, smoking and reading a magazine.

Snake has a few gadgets to aid him in battle. The OctoCamo suit mimics the appearance and texture of any surface, decreasing the probability of Snake being noticed. The Solid Eye device highlights items and enemies, and can operate in a night vision and a binocular mode. It also offers a baseline map, which indicates the location of nearby units. The latter function is also performed by the Threat Ring, a visualization of Snake's senses that deforms based on nearby unit proximity and relays them to the player.

Metal Gear Mk.II, later substituted by Mk.III, offers codec functionality and a means to the in-game menu for a large part of Snake's mission. It can be remote controlled to stun enemies, provide reconnaissance and interact with the environment. Its design is based on the namesake robot from Snatcher, a game designed by Hideo Kojima. It is also controlled during the beginning of each separate "Act", although the player is not able to utilize its capabilities during this time.

Whenever the Drebin menu is available, weapons, attachments and ammunition can be purchased via Drebin Points (DPs), awarded for on-site procurement of weapons already in the inventory and by initiating specific scripted events. The conversion rate between weapons and DPs depends on current battlefield conditions, with more-intense fighting yielding higher prices. Also, Drebin would purchase items from the player at a discounted price.

The Virtual Range, similar to the Virtual Reality training of previous titles, functions as a test facility for weapon performance and gameplay controls.