The gameplay of Snake Eater is similar to that of previous games in the Metal Gear Solid series. Snake, controlled by the player, must move undetected through a hostile, enemy-filled environment. Although Snake acquires various weapons (ranging from handguns to rocket-propelled grenades), the emphasis is on using stealth to avoid confrontations. Many objects and gadgets can be found along the way to aid in this, including motion detectors[6] to track hostile soldiers, and the Metal Gear series' trademark cardboard box, which Snake can hide under to avoid visual detection.[7]
Despite the fundamental similarities, Snake Eater introduces many new aspects of gameplay not present in previous Metal Gear games, including camouflage, a new hand-to-hand combat system called "close quarters combat" or "CQC", a stamina gauge, and an injury-and-treatment system.[7][8]
Two-thirds of the game is set outdoors in a Soviet Union temperate forest,[9] and using the environment to its fullest potential is often the key to success. Of the new features, particular emphasis is placed on camouflage and using the jungle environment itself (for example, climbing trees or hiding in tall grass) to avoid being seen by the enemy.[7] The advanced radar from previous games has been removed in favor of a simple motion detector and sonar system more suitable for the game's setting.
Snake uses camouflage to remain undetected. The "camo index" can be seen in the top, right-hand corner.
A percentage value called the "camouflage index" gauges Snake's exposure, on a scale from negative values (highly visible and attracting attention) up to 100% (completely invisible to the enemy).[10] To minimize visibility, the player must switch between different camouflage uniforms and face paints to blend in with the environment; for example, wearing a bark-patterned uniform while leaning against a tree, or wearing striped face paint while hiding in tall grass.[8] Other devices for camouflage, such as a fake gavial head to decrease chances of being detected in water, or a monkey mask, are also available.
The basic close combat from previous installments has been heavily refined and expanded into the CQC system. When unarmed or using a one-handed weapon, Snake can grab opponents and put them in a chokehold,[8] at which point a variety of actions can be performed, such as choking the enemy unconscious, throwing the guard to the ground, slitting the enemy's throat, or interrogating them at knifepoint to obtain information.[6][8] The context, the pressure applied to the button, and movement of the analog stick determine the action performed.
While previous games used only a simple life bar, Snake Eater keeps track of injuries over the entire body.[8] For example, a long fall could fracture Snake's leg, slowing him down until the injury is properly treated with a splint and bandage. Unless these injuries are treated, Snake will not be able to fully recover his health for some time.[8]
Besides the aforementioned features, there is also the need to rely upon native flora and fauna to survive.[8] This is manifested in a stamina gauge which constantly depletes during gameplay.[11] Failure to restore the gauge by eating has detrimental effects on gameplay, such as decreasing Snake's ability to aim his weapon and being heard by the enemy due to Snake's loud stomach grumbles.[8] Food can be stored in the backpack until it is needed. However, some types of food rot over time, and consuming rotten foods may result in Snake developing a stomachache, causing the stamina gauge to deplete faster.[7]
The PlayStation 2 version of Snake Eater include a minigame titled "Snake vs. Monkey", in which Snake has to catch Ape Escape-style monkeys.[7][6] In addition to containing tongue-in-cheek humor,[12] bonus items usable in the main game can be unlocked by progressing through various stages.[6]
