Successfully complete the game to unlock the "Password" option at the "Extras" menu. Then, enter one of the following case-sensitive passwords to unlock the corresponding bonus when a saved game is resumed or another game is started. Note: The bonuses will become available when the Mk II can first be used.

Desert Eagle Long Barrel: Enter "deskyhstyl" as a password.
Mk. 23 (SOCOM from Metal Gear Solid): Enter "mekakorkkk" as a password.
Mosin Nagant: Enter "mnsoymsyhnto" as a password.
"Desperate Chase" iPod song: Enter "THOMAS" as a password.
"Gekko" iPod song: Enter "GEORGE" as a password.
"Midnight Shadow" iPod song: Enter "THEODORE" as a password.
"Mobs Alive" iPod song: Enter "ABRAHAM" as a password.

In Act 4: Shadow Moses, Nuclear Warhead Storage B2, when at Otacon's office, he will ask you for the code. Enter one of the following codes instead of the one that Otacon mentions to get the corresponding bonus:

100,000 DP: Enter "14893" as a code.
"Opening - Old L.A. 2040" iPod song: Enter "78925" as a code. This song increases Snake's accuracy.
"Policenauts Ending" iPod song: Enter "13462" as a code. This song causes soldiers held by Snake to fall asleep when touched.

Successfully complete the indicated task to unlock the corresponding weapon:

Desert Eagle, Long Barrel: Get the Fox Emblem.
MGL-140 grenade launcher: Defeat Raging Raven.
MK 23: Search under the first truck you see in Act 4.
Patriot Future Assault Weapon: Successfully complete the game with a "Big Boss" rank. This weapon has infinite ammunition.
Rail Gun: Defeat Crying Wolf.
Race Gun pistol: Successfully complete the game.
Solar Gun: Collect the five statues (the four Battle Beauties and Frog Soldier/Haven Troopers) with non-lethal means on their respective idols.
Thor 45-70: Get the Fox Hound Emblem.
World War I pistol: Get the Hound Emblem.

Successfully complete the game to unlock the following ammo for purchase from Drebin:

Emotive Cry
Emotive Laughter
Emotive Rage
Emotive Scream
Smoke Grenade Blue
Smoke Grenade Green
Smoke Grenade Red
Smoke Grenade Yellow

Successfully complete the indicated task to unlock the corresponding piece of equipment:

Bandanna: Successfully complete the game without killing anyone, including Bosses. Alternately, purchase it from Drebin for 5 million Drebin Points after starting another game session after completing the game. This item gives you infinite ammunition.

Digital Camera: It is found in the Nomad vehicle during the mission intermission. Note: It will contain bonus photos if you wait until Act 4 to get the camera.

Mantis and Sorrow Dolls: Defeat Screaming Mantis.

Scanning Plug S: Log more than ten hours of online play time on the same profile as your single player game to unlock it for purchase from Drebin.

Stealth Item: Successfully complete the game without instigating an alert. Note: You can trigger a caution.

Successfully complete the indicate task to unlock the corresponding face paint:

Big Boss: Get the Big Boss Emblem. When you wear this mask, it causes enemies near you to cower in fear and/or run away screaming.
Corpse: Use over 41 continues in a single playthrough.
Crying Wolf: Defeat Battle Beauty (human form) Crying Wolf by non-lethal means.
Drebin: Acquire and keep over 60 weapons.
FaceCamo: Defeat Battle Beauty Laughing Octopus. This mask functions like the OctoCamo suit, but just on your head.
Laughing Octopus: Defeat Battle Beauty (human form) Laughing Octopus by non-lethal means.
Metal Gear Solid Snake: Successfully complete Act 3.
Otacon: Shock or run into Otacon at high speed with Metal Gear Mk. II during an interactive mission brief.
Raging Raven: Defeat Battle Beauty (human form) Raging Raven by non-lethal means.
Raiden A: Shock or run into Sunny at high speed with Metal Gear Mk. II during an interactive mission brief.
Raiden B: Shock or run into Naomi at high speed with Metal Gear Mk. II during an interactive mission brief.
Roy Campbell: Shock or run into Campbell at high speed with Metal Gear Mk. II during an interactive mission brief.
Screaming Mantis: Defeat Battle Beauty (human form) Screaming Mantis by non-lethal means.
Young Snake: Successfully complete Act 2.
Young Snake with bandanna: Successfully complete Act 2.

Successfully complete the indicate task to unlock the corresponding costume:

Altair's Rags (Assassin's Creed): Get the Assassin's Emblem.

Business Suit: Successfully complete the game.

Civilian clothes: Start the Eastern Europe level.

Corpse Camo: Use over 41 continues in a single playthrough.

Metal Gear Solid optical camo: Successfully complete the game without going into alert phase. Alternately, purchase it from Drebin for 5 million Drebin Points after starting another game session after completing the game. This camo makes you completely invisible.

Middle East militia disguise: Go to the Middle East militia safe house.

South American militia disguise: Go to the South American cove valley village.

Successfully complete the indicated task to unlock the corresponding song on Snake's iPod. Certain songs have an additional secret effect when played during the game.

Beyond the Bounds: In Act 4: Shadow Moses, Tank Hangar, after power is restored, return to the upper catwalk, and explore all the rooms. This song increases stun damage done by Snake from non-lethal weapons.

Big Boss: Get the Big Boss Emblem. This song increases stun damage and Snake's accuracy.

Bio-hazard: In Act 3: Europe, Midtown, hold-up a resistance soldier and body search him. This song causes soldiers held by Snake to scream.

Boktai 2 Theme: During the Act 2 mission briefing, go upstairs in the Nomad.

Bon Dance: Found in Act 2 in the Marketplace.

Destiny's Call: Received randomly from an allied or neutral militia or rebel soldier after Snake gives them a healing item. This song causes soldiers held by Snake to become enraged.

Flowing Destiny: In Act 4: Shadow Moses, Canyon, before leaving the canyon area, examine the rocky walls for a hole hiding the song. This song causes soldiers held by Snake to weep.

Inorino Uta: During the Act 1 mission briefing, go upstairs with the Mk II.

Level 3 Warning: Found in Act 1, Advent Palace.

Lunar Knights Main Theme: During the Act 4 mission briefing, go upstairs in the Nomad.

Metal Gear 20 Years History - Part 2: Found in Act 4, Warhead Storage Building B2.

Metal Gear 20 Years History - Part 3: Found in Act 2 at the South America Confinement Facility in the room with beds inside the house.

Metal Gear Solid Main Theme (The Document Remix): Found in Act 5 under the hatch to the left at the start of the area.

MGS 4 Love Theme/Action: Received randomly from an allied or neutral militia or rebel soldier after Snake gives them a healing item. This song causes soldiers held by Snake to weep.

On Alert: Found in Act 3, Midtown N Sector.

One Night in Neo Kobe City: Found in Act 3, Midtown; hold-up a PMC soldier.

Opening - Old L.A. 2040: In Act 4: Shadow Moses, Nuclear Warhead Storage B2, input "78925" into Otacon's lab computer. This song increases Snake's accuracy.

Policenauts Ending: In Act 4 Shadow Moses, Nuclear Warhead Storage B2, enter "13462" into Otacon's lab computer. This song causes soldiers held by Snake to fall asleep when touched.

Rock Me: In Act 2: South America, Confinement Facility, search the island in the south-eastern quadrant. This song increases the amount of life recovered from items and other means.

Sailor: In Act 2 South America, Vista Mansion, look between the east wall and a cargo container. This song increases the amount of life recovered from items and other means.

Shin Bokura No Taiyou Theme: During the Act 3 mission briefing, go upstairs in the Nomad.

Show Time: Received randomly from an allied or neutral militia or rebel soldier after Snake gives them a healing item. This song causes soldiers held by Snake to scream.

Snake Eater: Get all 40 game clear Emblems. This song increases the amount of life recovered from items and other means.

Subsistence: Play one game of Metal Gear Online, starting the match with at least two players. This song increases Snake's accuracy.

Test Subject's Duality: Found in Act 3, Midtown S Sector.

The Best Is Yet To Come: Found in Act 4, Snow Field just before the "Disc Change" Codec transmission.

The Essence Of Vince: Found in Act 3, Echo's Beacon.

The Fury: In Act 2: South America, Cove Valley Village, search inside the fire-ravaged house. This song causes soldiers held by Snake to become enraged.

Theme Of Solid Snake: Found in Act 1, Millennium Park.

Theme Of Tara: Found in Act 1, Militia Safehouse just before seeing the unmanned flying-bomber on the table.

Warhead Storage: Found in Act 4, Tank Hanger, upper floor ventilation shaft.

Yell (Dead Cell): Found in Act 4, Casting Facility North.

Zanzibarland Breeze: Found in Act 1, Urban Ruins before intermission sequences.

Successfully complete the indicated task to unlock the corresponding Emblem:

Ant: Shake 50 enemies for items.

Assassin: Successfully complete the game with killing more than 50 enemies with the knife, having over 50 CQC holds, and getting discovered less than 25 times.

Bear: Choke 100 enemies to death.

Bee: Use the Scanning Plug S or Syringe on 50 enemies.

Big Boss: Successfully complete the game on the Boss Extreme difficulty without dying, instigating no alerts, killing no enemies (including Bosses), using no life recovery items, using no stealth suit or bandanna special items (can possess, but not activate), and with a completion time of less than 5 hours.

Blue Bird: Give friendly soldiers 50 items.

Centipede: Get fewer than 75 alert phases, fewer than 250 kills, and use over 25 continues.

Chicken: Get over 150 alert phases, over 500 kills, use over 50 continues, use over 50 recovery items, and complete the game in over 35 hours.

Cow: Activate over 100 alerts.

Crocodile: Have over 400 kills.

Eagle: Get 150 headshots.

Fox: Successfully complete the game on the Naked Normal or higher difficulty without dying, instigating no more than five alerts, killing no enemies (including Bosses), using no life recovery items, using no stealth suit or bandanna special items (can possess, but not activate), and with a completion time of less than 6 hours.

Fox Hound: Successfully complete the game on the Big Boss Hard or higher difficulty without dying, instigating no more than three alerts, killing no enemies (including Bosses), using no life recovery items, using no stealth suit or bandanna special items (can possess, but not activate), and with a completion time less than 5 hours and 30 minutes.

Frog: Dive or roll 200 times.

Gecko: Press against walls for a total of one hour.

Giant Panda: Successfully complete the game after 30 cumulative hours of game play.

Gibbon: Hold up 50 enemies.

Hawk: Be admired by 25 friendly soldiers.

Hog: Get 10 combat highs.

Hound: Successfully complete the game on the Naked Normal or higher difficulty without dying, instigating no more than three alerts, killing no enemies (including Bosses), using no life recovery items, using no stealth suit or bandanna special items (can possess, but not activate), and with a completion time less than 6 hours and 30 minutes.

Hyena: Pick up 400 dropped weapons.

Inch Worm: Crawl on the ground for a total of one hour.

Jaguar: Get over 76 alert phases, less than 250 kills, and less than 26 continues.

Leopard: Get over 76 alert phases, less than 250 kills, and at least 26 continues.

Little Gray: Collect all 69 weapons.

Lobster: Crouch for a total of 2 hours and 30 minutes.

Mantis: Use no continues, get no alerts, and have a completion time less than 5 hours.

Octopus: Get no alert phases.

Panther: Get over 76 alert phases, over 251 kills, and less than 26 continues.

Pig: Consume over 40 food items.

Pigeon: Have no kills.

Puma: Get over 76 alert phases, over 251 kills, and at least 26 continues.

Rabbit: Look at 100 Playboy pages.

Raven: Successfully complete the game in less than five hours.

Scarab: Perform 100 dive rolls.

Scorpion: Have less than 75 alert phases, less than 251 kills, and less than 26 continues.

Spider: Have less than 75 alert phases, at least 251 kills, and at least 26 continues.

Tarantula: Have less than 75 alert phases, at least 251 kills, and less than 26 continues.

Tortoise: Hide inside a cardboard box or drum barrel for at least one hour.

Wolf: Use no continues and no recovery items.

Successfully complete the game to unlock new combat vests.

Successfully complete the game to unlock the Big Boss Extreme difficulty.

Successfully complete the game, and save when prompted to create a cleared saved game file. Start another game session, encounter Mk II in Act 1, and load the cleared saved game file to get your Drebin Points, weapons, ammunition, items, and special items from your previous game.

If you fight Mantis with a Sixaxis controller, the ending is different than if you were using a DualShock 3 controller.

First, acquire the drum can. You do this by finding the soldier that is hiding in the can, and using it as a bathroom. After that, go up ahead a few feet, where you will see three crates. When you have gone past them, you will see just two crates. You will also see about three rebel soldiers fighting. One is carrying an RPG and the other two have machine guns. They will die and respawn continuously. You will have a chance to pick up the RPG after the soldier has died three times. Do so because each RPG is worth 6,000 Drebin Points. The important thing is to stay anywhere behind the two crates, otherwise the trick will not work. Going further than the two crates will stop the respawning loop of the soldiers dying. The only way to get the RPG without breaking the respawning loop is to use the Mk II.

Set the PS3 system date to a Wednesday or Sunday, and Drebin will have cheaper prices. Additionally, all of Drebin's prices are cut by 50% during Act 5.

Save the game during Act 1. Go to the Mission Briefing screen, and select the saved game from Act 1. Press Square to control the Mk II while on the plane. Move the Mk II upstairs, and search for an extra battery. Collecting it will double the operating life of all battery-powered devices in the game.

The statues required to unlock the Solar Gun can be found at the following locations:

Frog: In Act 1: Middle East, Advent Palace garage, atop the Nomad vehicle.
Octopus: In Act 2: South America, in the Research Lab Boss room, upper right room.
Raven: In Act 3: Europe, on the top floor of the human phase of the Boss fight.
Wolf: In Act 4: Shadow Moses, behind Snake's starting spot in the human phase of the Boss fight.
Mantis: In Act 5: Outer Heaven, near the northern-most door during the human phase of the fight.

Experience the following audio flashbacks to get 1,000 Drebin Points for some of them:

Find the crop circle near the river while tracking Naomi in Act 2 after the Laughing Octopus fight (flashback of the Colonel acting strangely in Metal Gear Solid 2).

Find the Hind (flashback of the end of the Hind confrontation).

The middle of the helipad (flashback of Hind D speech).

The small shack to the West of the area (flashback of "A surveillance camera?!").

Enter through either of the vents instead of the door (flashback Master Miller's introduction).

Stand near the tank hangar's door (flashback of Meryl's "Where I can see you" speech).

Stand in the decontamination room before the hallway to Otacon's office (flashback of Cyborg Ninja fighting Genome Soldiers).

Inside Otacon's lab (flashback of Grey Fox's introduction).

Stand in the filled-in trench leading up to the Comm Towers (flashback of Meryl telling Snake to continue without her).

Climb as far as you can up the Comm Tower nearest where you enter and walk around (flashback of beginning of the Hind confrontation).

In front of the other Comm Tower, facing the exit (flashback of Otacon's "What are you fighting for?" speech).

Stand near the door leading back to the room where you fought Vulcan Raven (flashback of Raven's final speech).

In Shadow Moses, near the elevator (flashback of Infiltration speech).

Return to the crashed Hind chopper after the Crying Wolf fight (flashback of Liquid Snake being shot down).

Aim the Mk.23 SOCOM while at Shadow Moses (Snake will say "Just like old times").

Move the camera view directly overhead and move around (Snake will say "Just like old times").

When starting a new game, you are shown two random commercials. You can change the channel by pressing Up and Down to get new commercials. There is also a Hideo 1 and Hideo 2 channel, which are like Video 1 and 2.

At the start of the game when the commercials are on, you can press X to cycle through different channels. You can see a segment where David Hayter is being interviewed wearing a Solid Eye.

During an intermission sequence, press D-pad Up to zoom the camera in, then use the Right Analog-stick to pan the camera around. The harder you press Up, the more zoomed in the camera view. Also, some intermission sequences have prompts to see it through Snake's eyes by holding L1 (look for the icon at the top left of the screen) or view flashback images by repeatedly tapping X when a prompt appears (look for the icon at the top right of the screen). You can also pause an intermission sequence by pressing Start.

During the following intermission sequences, press L1 to see secret events:

Laughing Octopus: Laughing Octopus quickly leaps away outside the window during one of the L1 sequences when you first meet Naomi.

Naomi's chest: In Act 2, after Snake loses his Psyche when Namoi tells him how long he has, press L1 to look at her chest and recharge Snake's Psyche.

Naomi upskirt: In Act 2, when Snake's talking to Naomi and drops his cigarette, use the hidden L1 option to look up her skirt.

Psycho Mantis' ghost: During the first intermission sequence with Beauty and the Beast, after using the option to look through L1, look to the left to see the ghost of Psycho Mantis.

Sorrow: During the Psycho Mantis intermission sequence, keep L1 held. When Psycho Mantis disappears, you will hear Sorrow say something. Hold L1 (even though you are not prompted), and you will see Sorrow. Press X to start a flashback.

During the mission briefings, touch the the radio on the table upstairs with the Mk II, and it will play music.

By switching the radio on and off in Act 4, you will get different songs, including a remixed version of the "Love Theme" from Super Smash Bros. Brawl and the ending theme from Policenauts.

Shake the Sixaxis controller to return Snake's OctoCamo to its neutral (black and blue) appearance. Note: This can also be done during intermission sequences.

When a character is first introduced, press R2 to view that character's motion capture actor instead of his or her voice actor.

Sit in a box to reduce stress faster.

If something during an intermission sequences causes Snake's Psyche gauge to decrease, rapidly tap X to replenish it.

To switch between crawling and crouch-walking (and back) faster, move forward while pressing X. Use this trick to get prone behind cover quickly after crouch-walking past an enemy.

Shoot the tranquilizer gun at your target. Get close to the sleeping target, and go into the crouch position. An icon will appear to wake the target up. Press [Action] to wake your target. When he or she is about to wake up, position yourself at either side or the back of the target. Aim your gun, and Snake should hold-up the target. This is an easy way to do CQC and knife kills if you want to get the Assassin's Creed Emblem and costume.

There are dumpsters throughout the game which you can use to hide. Move in front of them, and press Triangle when the prompt appears. Once inside, if you have a handgun, The Operator for example, you can hold L1 to lift up the lid of the dumpster and aim your gun from inside.

While throwing a grenade, lightly hold L1 (default [Aim]) instead of holding it down completely.

PMC soldiers will ignore you when wearing Otacon's or one of the Beauty's face paints if you are not attacking or displaying a weapon. This allows you to track the Resistance easier.

Instead of rotating the Right Analog-stick to control the iPod, use Triangle, Square, Circle, and X.

Equip the Sorrow Doll, and have the camera from the Nomad. You can use that camera to find thirty ghosts in Shadow Moses. After taking pictures of them, they can be viewed in the photo album with a new option. Note: The doll is only needed to see the ghosts prior to taking the photographs.

In Shadow Moses, when you return to Otacon's office to shut down security and turn on the power, take a photograph of the area to the left of the Policenauts poster. When viewed, there will be a superimposed image of Hideo Kojima's face.

Take a picture of the wolves after the Crying Wolf battle. Sniper Wolf's face will appear in the corner.

Do not pick up the camera during the briefing when it first becomes available. Wait until Act 4 to get the camera, and it will have some funny pictures of Naomi and Sunny playing around in the kitchen.

While tracking Naomi, get to where there is a PMC soldier standing next to a claymore. Move northeast from there to find a metal plate on the ground with signatures and handprints from the game's developers. Note: Lay down on it to get the handprint design for your camouflage. Register it to memory, and you can use it whenever desired.

When you are tracking Naomi's footprints in Act 2 after the Laughing Octopus fight, you will arrive to a river. Instead of crossing the river, look to your left. You will see another set of footprints. Follow these, and they will lead you to a crop circle where you will hear some strange dialog by the Colonel about an alien abduction.

If you kill a large enough number of enemies in a conflict zone, you will hear Liquid from Metal Gear Solid say "You enjoy all the killing, that's why!", and Snake will vomit. Note: You can delay the vomiting by hugging the wall. The next time you kill someone, however, it will happen again until you finally vomit.

Use the Solid Eye with the Raiden A mask to make Snake's eyes glow.

In Act 1, go to the place with the two broken statues. Press Triangle to climb up on the empty statue pedestal in that area. Press Triangle again, and Snake will assume a statue position, and the OctoCamo will blend in. Keep pressing Triangle, and Snake will grab the crotch of the statue next to him and eventually break off that part of the statue.

When wearing the Altair costume after unlocking it, there are some changes Snake will make to his posture. First, he stands with his hands by his sides and outstretched just like Altair, as opposed to hanging down in front of him with his fists clenched. This change will only occur when you do not have a weapon equipped. Second, where Altair had the ring finger on his left hand missing, Snake bends his up to give a similar visual effect. He will even keep his finger bent during intermission sequences in which the costume you are currently wearing appears.

In Act 1, when in the underground hanger/cave, you can use the Mk II to listen to a wounded PMC soldier's conversation. He will talk about the Beauty And The Beast group before you actually meet them.

After defeating any of the four Beauties, there is a second round where they walk towards you, trying to grab Snake. During this phase, run from them for three minutes, and the screen around you and the Beauty will turn white. Take out the digital camera you obtained from the mission briefings. The Beauty will stop chasing you and do sexy poses for your camera.

Play the "Oishii ChuhanSeikatsu" Japanese pop song on your iPod while fighting a Beauty. She will start dancing. If you aim a camera at her, she will pose.

You can buy a magazine with pictures of the models that the Beauty And The Beast unit were based on from Drebin.

Flick the TV remote with the Mk II to get Japanese models to appear on the television.

Flick the remote for the screen Campbell talks to you on with the Mk II to see pictures of ladies in their underwear.

When Naomi is in the Nomad and on the computer talking, use the Mk II to look at Otacon's computer. His webcam is focused on Naomi's cleavage.

During the third playthrough of the game, when you first meet Rose she will be wearing a new shirt.

When you speak with Rose on the Codec, shake the Sixaxis to make her breasts move.

To look through the Playboy magazine, press R1, then go into first person view. Then, hold L1 and press Circle to go through the pages. If the game puts you in third person view, press Triangle to enter first person view to see the models.

There are two posters of Akina Minami in the Vista mansion. Look at them in first person view, and Snake will say her name and his Psyche gauge will increase.

Clear an area of all enemies in Act 1 or Act 2. All the allied soldiers will begin to cheer. No additional enemies will respawn in those areas if you return.

While fighting Psycho Mantis, CQC Meryl, and inject her with the syringe to take her safely out of the fight. Note: Mantis might take control of her again after awhile.

Shoot five tranquilizer rounds into the legs of a Gekko. It will collapse and thrash around on the floor. You can walk past without being spotted while that is happening.

When you are in the basement lab at Shadow Moses and the Gecko appears, send the Mk II to the electric console to the right of the elevator. Note: This is the same console that was destroyed with the rocket in the original Metal Gear Solid. Use the Mk II to reactivate the electric floor and destroy the Gecko.

In the first part of the battle against Vamp, after you get his health low enough, he will fall down. As he gets up, grab him in a CQC hold, and inject him with the syringe that you obtained earlier. This will disable his Nanites and make him mortal.

You do not have to deplete Vamp's health before CQC grabbing him. Hide and sneak up behind him for a CQC.

Instead of depleting his life, use a tranquilizer gun and shoot his head. He will fall down, immediately giving you the chance for the CQC.

Crawl around the vents in Shadow Moses to encounter Rats. When they see Snake, "!" will appear above their heads, accompanied with a sound. They will run away. Keep chasing them, and they will repeat the "!" alert. Following the rats is a good way to get in. If you call Otacon after you see the rats, Snake will talk about them and how they helped him before.

If you complete a chapter after 4 a.m., a message will come up during the install screen (Snake smoking), suggesting that you get up and do some stretches, and saying that you have been playing awhile.

When tailing a resistance member, if you look behind Snake, you will occasionally notice a man with a hat and trenchcoat also tailing him. This is how the Scarabs found the hideout. If you try to shoot him, he will duck away around the corner and disappear.

Wear one of the Beauty's face paints in Act 3. The Resistance will ask Snake, "Hey, are you looking for a real man?" The vehicle patrols will also honk at you as they drive by.

Call Otacon a few times in Shadow Moses at the part where Snake originally fought Vulcan Raven in the tank (and is now where two sleeping Geckos are found). Otacon will say that "Snake is the craziest bad ass who ever lived."

Try to access any feature that requires Internet connectivity while not connected. A chat menu featuring Otacon will appear, and he will try to give you technical support.

During the Act 5 mission briefing, immediately after Otacon lights Snake's cigarette, he adjusts his glasses. When he does this, you can see a reflection of Naomi on their lenses.

Play the "Oishii ChuhanSeikatsu" Japanese pop song on Snake's iPod. During that song, press Start to see Sunny dancing at the bottom left corner.

In Act 3, while you are trailing the Resistance member, listen to his whistle. It is what Sunny will hum during mission briefings.

During the fight with Laughing Octopus, lie down on one of the beds face up. She will straddles you, then Snake will knock her off.

At the third part of the final fight, when Liquid Ocelot grabs Snake by the neck, allow the controller to idle. After some time, Liquid Ocelot will kiss Snake on the cheek.

In Act 5, if you die and wait an extended period to select "Continue" or "Exit", you will hear Liquid say "It's not over yet, brother!", and the "Exit" button will change to read "Exist". Using it will move your selection over to "Continue", but then you will have the option to exit again.

After dying, call Rose to hear a conversation about Snake having dreams of being killed or a comment from Snake saying that he feels like he has died once before.

During the Act 5 mission briefing, use the Left Analog-stick to change the projection's height on the screen. This will make some of the attendees angry.

Tranq Crying Wolf, and the wolves in that area will follow you.

In Act 4, kill one of the wolves after you defeat Crying Wolf. The others will attack you. Call Otacon, and he will wince. Call Rose, and she will tell you that animal cruelty is the first sign of criminal behavior, and says that she will have you psychologically assessed if you continue to kill them.

Hold up a FROG soldier, and body search them. When you would normally ball crush a male prisoner, they will say "You men are all the same", "You're disgusting!", or "Ugh" and kick you.

When you search a FROG soldier when they have no items, she will giggle as if ticklish.

When you search a FROG soldier and touch her chest, sometime she will moan or say "You're pretty good at this".

Sneak through the first part after the opening, and go through the buildings. At the building to the right of where the APC shows up, crawl under the rubble. You will see a militia soldier get brutally shot after pleading for his life.

Whenever Snake is smoking there is always a no smoking sign behind him.

When tracking Naomi in Act 2, look to the right when crossing the river to see a guard relieving himself.

Follow the resistance member in Act 3 to see him urinating in the fountain in the small park.

In the central park during Act 3, there is a statue that Snake can interact and imitate. Stay in that pose until a resistance member appears, and he will urinate on you.

There is a gun called the "Stun Gun" which is actually a reference to one of Hideo Kojima's older games, Boktai: The Sun Is In Your Hands for the Game Boy Advance. This is confirmed when Solid Snake raises the gun towards the sun to recharge and yells out "Sunlight", much like the main character did in Boktai.

After defeating Screaming Mantis and immediately after Psycho Mantis vibrates your controller, keep pressing X to see Hideo Kojima.

If you prolong the Psycho Mantis fight long enough, the game will show the opening screen, except the word "Kojima" will replace "Konami". The game will then resume the Psycho Mantis fight.

Press L1 to examine the .50 Cal Anti-Material Sniper Rifle to see "Recommended by Hideo Kojima."

When Snake hides from the two Irvings next to the box of watermelons, the box reads "No Place For Hideo."

You can see a ghost image of Hideo Kojima in Otacon's lab using the camera. It is between Policenauts and the poster that from a distance reads "Final Fantasy VI".

On the computer, the term "Video 2" is called "Hideo 2".

When the game first begins, the channels on the television are numbered 15, 16, 23, and 42, which are part of the number sequence from the television show Lost.

The monitor for the PC used by Sunny has a Lunar Knights screensaver.

During the Act 1 FROG attack sequence, attack Meryl. She will say the same things she said when you attacked her in Metal Gear Solid.

The password Johnny puts in to disable the laser trip trap is "MERYL SILVERBURGH".

You fight Crying Wolf in the same area you fought Sniper Wolf.

You can find the Hind D still in the Snowfield where you fight Crying Wolf.

During the Mantis fight, switch your controller ports when your television switches to "Hideo 2". Otacon will come on the Codec and notify you that the trick does not work twice. You will also get a suggestion about destroying the bust.

When you die in Act 4, the "Game Over" music from the first Metal Gear Solid will play.

After you die during the final Boss battle and select "Exit", it quickly changes to "Exist". Liquid Ocelot says "Not yet Snake, it's not over yet" and it moves the pointer back to "Continue". This is a reference to a quote by Liquid in the original Metal Gear Solid.

Call Rosemary with a ration equipped to see a reference to a sequence that happened in Metal Gear Solid 2, when Raiden calls Snake on the Codec with a ration equipped and comments about Rose's cooking.

When Drebin and Little Grey jump off of the Stryker, they will land in Naked Snake's pose from Metal Gear Solid 3, when he first arrives for the Operation Virtuous mission.

Equip the Patriot gun to hear music from Metal Gear Solid 3: Snake Eater.

Press L1 to view the description for the Mosin-Nagant. It mentions The End and his sniper duel with Big Boss.

If you stare at Meryl's breasts, she will blush similarly to how she did in Metal Gear Solid: The Twin Snakes.

Look at the two puppets dangling from Screaming Mantis. The two puppets appear to be Psycho Mantis and The Sorrow from previous Metal Gear Solid games.

When Snake and Naomi talk about war changing and how it used to be "just a game", all of the Metal Gear Solid titles appear in an indexed list. After MGS4, there are a few boxes titled "In Production."

When you first enter Big Mama's hideout and the guards start talking about Snake, press L1 to see posters from Metal Gear Solid, Metal Gear Solid 2, Metal Gear Solid 3, and Metal Gear Solid: Portable Ops.

In the Nomad briefing missions, take control of the Mk II, and go to the right of the helicopter. There are three separately caged chickens, each with its own label: "Solid", "Liquid", and "Solidus". This is a reference to the three Big Boss clones. A further reference to those chickens happens at the very beginning of Act 1 when Sunny is cooking eggs. She says "Only two eggs? Solidus must've taken the day off."

The rubber duck in the upper gantry of the Nomad can also be found in Capture The Flag mode in Metal Gear Online; in the GA-KO camouflage in Metal Gear Solid 3; and floating in the flooded Shell Core in Metal Gear Solid 2.

When you are in the final showdown with Liquid, when it enters the third stage of the fight, Liquid will do Ocelot's signature hand gesture.

Otacon has a model of Rex beside his computer.

During a Codec transmission with Campbell, he will talk about the training PMC soldier's went through. Snake says similar to "...better than those VR missions".

Drebin sells laundered guns, called "Naked Guns". Drebin's name is a reference to Frank Drebin from The Naked Gun movies.

One of the backgrounds on Otacon's computer is a scene from Policenauts.

In the Act 1 briefing, there is a PS3 on the second floor of the plane.

During the Act 1 briefing, go upstairs on the Nomad to see Sunny unpacking her PS3 and PSP.

In the Act 2 briefing, there is a PlayStation 3 on the table.

After you defeat Crying Wolf in Act 4, Otacon will call you as you enter that building and tell you to change discs. He then catches himself and starts talking about Blu-Ray and the PlayStation 3.

When you send out the Mk 2, look over Snake's shoulder by tilting the camera. He is using a PlayStation 3 controller to control it.

Use the Codec to call Rose during the fight with Screaming Mantis. Campbell will tell you to switch controller ports. Rose will get angry and say there are not any controller ports because this is on a PlayStation 3.

If you use a Sixaxis controller against Psycho Mantis he says, "What? No vibration!" and the flashbacks show the Sixaxis.

During the Act 2 briefing, Sunny is playing a PSP. The game is Penguin Adventure, a 1986 title for the MSX computer system, which was Hideo Kojima's first game.

The suit Snake wears in Act 3 is a homage to Gillian Seed, from Snatchers.

The "Dr. Madnar" mentioned in Act 3 is a reference to a scientist from Snatchers.

In Shadow Moses when Snake is about to get on the lift to fight Vamp, watch as the camera circles around the lift area to see a Darth Vader helmet on the floor.

In the Act 5 briefing, while Mei Ling is explaining the situation to everyone she says something about it being an impenetrable fortress or something similar. Snake then says, "He has his very own Death Star."

Leeroy Jenkins' grave can be seen directly behind Big Boss's. It will come into view when the camera pans around the area before Old Snake puts the gun into his mouth. You can also see it again while Old Snake is carrying Big Boss to The Boss' grave.

When you look at the briefing scene, Otacon's computer desktop picture is the main character from Zone Of The Enders, another game directed by Hideo Kojima.

The following weapons are available in the game:

Pistols

1911 Custom
Desert Eagle (originally used by Meryl)
Desert Eagle Long Barrel
Five Seven (gun used by Snake when he infiltrated Galuade)
Glock 18C
GSR (.45)
Mk 2 Pistol (Tanq)
Mk.23 SOCOM (Snake's main handgun from Metal Gear Solid)
Operator (Colt .45 with extended barrel)
PMM
PSS
Race Gun (fires ricochet bullets)
Solar Gun (causes enemies to drop weapons and does extreme damage to Vamp)
Thor .45-70 (rifle pistol)
Type 17 (broom handle machine pistol)

Sub-machine guns

Bizon
M-10
MP5sd2
Mp7
P90
Patriot (The Boss' weapon; has unlimited ammunition)
VZ. 83 Skorpion

Assault rifles

Ak102
An94
FAL Carbine
G3A3
M4 Custom
Mk.17
XM8

Sniper weapons

DSR-1
Heavy machine guns
HK21E
M14EBR
M60E4
M82A2
MK.46 Mod 1
Mosin-Nagant (The End's sniper rifle)
PKM
RAIL GUN
SVD
Tanegashima (old flint lock that is very slow to reload, 33% of hits causes a whirlwind that carries off enemies making them drop items)
VSS

Shotguns

M870 Custom
Saiga-12
Twin Barrel

Grenade launchers

MGL-140
XM25

Rocket launchers

Fim-92A (Stinger)
Javelin
M72A3
RPG-7

Weapon modifiers

Dot sights
Flashlights
Fore grips
Grenade launchers
Laser sights
Masterkey (under barrel shotgun for assault rifles)
Scopes
Suppressors

Others

C4
Chaff grenade
Claymore
Grenade
Knife
Molotov cocktail
Sleeping gas mine
Sleep gas satchel charge
Smoke grenades (yellow, red, blue, green)
Stun grenade
White phosphorus grenade