Upon loading the game, the "Press Start" screen is displayed. Pressing START brings up the main menu, which contains the following options:
- New Game
- Load Game
- Briefing Files
- Snake vs. Monkey
- Demo Theater
Starting a New Game/Loading a Saved Game
If you are playing the game for the first time, select "New Game" from the main menu. This allows you to start a new game from scratch, with no special or carried-over items.
After selecting this option, you will be greeted with three options (four if playing on Subsistence):
- I'm playing the MGS series for the first time!
- I like MGS1!
- I like MGS2!
- I like MGS3! (Subsistence only)
Although the option you chose will not have any bearing on the actual gameplay, selecting "I like MGS2!" makes Snake start the game wearing the Raikov mask (including throughout the opening scene and in a following bonus sequence). If you choose "I like MGS3!" you get three new uniforms:
- Desert Tiger
There will then be four difficulty levels to choose from (six if you have already completed the game once). The level you choose will affect the game's specifications; for example, on higher difficulty levels, enemy senses are more sensitive and their attacks also cause more damage, whilst Snake can carry less ammo and takes longer to heal injuries. The only exception to this rule is "European Extreme"; it is identical to Extreme in every way except that the game will end automatically when Snake is spotted, rather than when he dies. The difficulty levels are:
- Very Easy
- Extreme (Only available after completing the game once or in Subsistence by selecting I like MGS3!)
- European Extreme (Only available after completing the game once or in Subsistence by selecting I like MGS3!)
Choosing "Load Game" from the main menu will allow you to continue saved games from where you last left off. Since you have the option to save completed games, loading these games will grant certain privileges (see Secrets). However, note that while some MGS games allow you to change the difficulty upon loading a completed game save for the subsequent playthrough, MGS3 is not one of these games.
Choosing this option allows you to view Major Zero's briefings for the Virtuous Mission and Operation Snake Eater. Obviously, you can only view briefings that you have already unlocked in-game, and this option will not appear if there are no saved games.
"Snake vs. Monkey" is a mini-game that involves a hunt for monkeys in the jungle. It essentially a crossover between Metal Gear Solid and Ape Escape, and it serves both as a bit of fun away from the main game and a good way to practice the controls. And if you managed to complete all stages with new high score there will be bonus for you.
The "Demo Theater" allows you to view all the cutscenes in the game that have been previously unlocked. This option appears after completing the game once.
This menu allows you access additional features of the game such as "Basic Actions" and "Photo Album".
Whilst playing the game, there are several elements visible on the screen. The bar in the top-left of the screen is the health bar. The health bar will decrease when Snake is hurt, and if the bar empties, Snake will die. Any red portion of the bar signifies a serious injury that must be healed (see below). The bar directly below it is the stamina bar, which decreases gradually over time (the speed at which this happens is based on certain conditions), and Snake's performance will be affected by a low or empty bar. Stamina can be replenished by eating.
The stamina bar will also function as both the O2 gauge and the grip gauge. When Snake is underwater or hanging, it will turn blue and decrease more quickly.
In the top-right, the camouflage settings are visible. The current choices for face paint and uniform are displayed above and below respectively, whilst the percentage sign—the camo index—shows exactly how effective the current camouflage setup is (while 100% indicates invisibility, 70% is usually enough to remain unseen. Any particularly effective camo index will appear in blue and any dangerously low camo index will appear in red).
The number in the top-center shows the current alert level (see below). In the bottom corners are the items and weapons (left and right respectively); hold L2 or R2 to access their respective windows.
Obviously, as this is a stealth mission, the aim is to not be spotted. If Snake is seen by an enemy, the game will enter "alert" mode (signified by a red "alert" displayed on the screen accompanied by a timer), in which the enemy/enemies will be chasing and attacking Snake. Once the accompanying countdown reaches zero (it will decrease any time Snake is outside the enemy's sight), the alert will drop to "evasion".
In evasion mode, the enemy will be actively looking for Snake, but will not know exactly where he is. When that countdown reaches zero, "caution" mode will then be activated.
Caution mode, unlike alert or evasion, does not count as an alert (i.e., if you are going for a no-alert playthrough, you are allowed to enter caution mode, but not alert or evasion mode). During the caution phase, the enemy will not be alerted to Snake's presence, but will still be extra cautious, and there will be extra guards on patrol.
This sequence is not strict. A caution mode can be instantly activated if an enemy encounters evidence of Snake's presence, such as a dead guard or a shot fired nearby. Depending on the seriousness of the discovery that raises caution (i.e. a dead guard vs. a sleeping one), the guard may or may not call for reinforcements.
If a guard sees you, an alert will occur, but if you kill or disable the guard before he has a chance to attract attention or call for help on his radio (you can avoid this by shooting the radio to disable it), the alert will instantly cease.
Under normal circumstances, it will take a guard a moment to realise what exactly he is seeing upon noticing Snake, giving you a chance to disable him. However, during any alert or if a guard is suspicious, this brief grace period does not occur. If a guard either discovers you or evidence of your presence, an exclamation point will appear over his head: red for the former, blue for the latter. Should he should hear or see something that arouses his curiosity (such as Snake running in the distance or a knock on the wall), a question mark will appear over his head instead.
Radio and Saving the Game
The radio will allow Snake to keep in contact with others he has met, replacing the Codec from the other games. This will include his support team and other radio-possessing people he encounters on his mission. In case you forget frequencies, Snake will remember important frequencies so that you can select them from a list. You can also use the D-pad to select a frequency manually. Going into the radio will pause the game.
The radio is also used to save the game. As with all the MGS games, the frequency for saving data is 140.96, which will patch Snake directly through to Para-Medic.
The "Survival Viewer" is the pause menu of the game, accessed with the START button. Inside it, there are six options:
In this game, you can use camouflage to blend into your environment, eat food and cure serious injuries with medical supplies. All these are managed in the Survival Viewer, and are features new to the MGS series. The first option, "Camouflage", allows you to determine how visible you are sight-wise based on your selected face paint and uniform. Note that this does not allow you to determine how conspicuous you are; although the camouflage menu also holds disguises such as the Scientist and Officer outfits, the camo index will not, for example, display a 100% index when the Officer disguise is activated in Groznyj Grad, even if it does allow you to walk freely without fear of discovery in plain view of guards.
The "Backpack" is a standard-issue U.S. Army backpack used by Naked Snake. It is used to carry all of Snake's weapons and items, as well as all the food he has collected. As there is a limit to what equipment can be actively available for use from the in-game item/weapon windows, equipment not in use is stored in the backpack, whilst equipment ready for selection is taken out and readied for Snake's use. The more equipment Snake has taken out of the backpack and is actively carrying, the more stamina Snake will burn.
All the food available to Snake for consumption is listed in the "Food" menu. The backpack can hold a maximum of 18 animals and plants, though three of those slots are cages reserved for live animals. Some animals, specifically large ones such as the Indian Gavial, cannot be captured alive.
In the "Cure" menu, Snake can use medical supplies to heal his wounds. There are two types of cures: Medicinal and Surgery, accessed through the L2 and R2 buttons respectfully. The former is used to heal poisonings, stomach trouble etc., whilst the latter is for healing wounds such as broken bones, bullet wounds or leeches. Extra medicine and medical supplies can be harvested from some plants and animals, or found on enemies. It is unlikely that you will run out of medical supplies.