If for whatever reason you're unable to use the second controller port, Colonel Campbell will eventually reveal an alternate way to beat Mantis: destroying the busts in the room.
If you don't take the SOCOM pistol from the truck in the heliport, the cutscene when Meryl lets you out of the cell will be different. Snake will push aside the barrel of her gun instead of aiming back at her.
If you attack Meryl when she's following you, she'll slap you and knock you down normally, although if you hide in a box afterwards, she can't hit you back. However, if you do this in an area with wolfdogs that are friendly to her, she'll instead whistle and cause one of them to pee on your box, and wearing that same box afterwards will cause the wolfdogs to ignore you due to the scent.
Having Sniper Wolf's handkerchief equipped will cause the wolfdogs to follow you without attacking and it doesn't require any additional gimmickry from player's part, but once Snake returns it to Wolf after he kills her, you obviously can't use it anymore and need to resort to the box trick described above.
Beating Ocelot quickly has him compliment you in the following cutscene. Beating him after a longer fight changes his dialogue accordingly.
One of the most famous things in the original MGS was the box warp. By climbing onto a supplies vehicle and equipping a box from elsewhere in the game, you could be transported to that location.
If the player is fighting the Hind with the Mono sound setting on, an optional Codec call can be accessed where Colonel Campbell expresses disappointment that Snake doesn't have Stereo, or Naomi stating that Snake isn't any less of a man for using Mono.
In the fight with the Cyborg Ninja, he makes a big scene out of the fact that you can fight hand-to-hand. Indeed, most of your weapons are useless. You can, however, freeze him for a few seconds using a chaff grenade. If you do, not only can he criticize Snake for not being what he was, he can also break the rules himself and use his sword.
On the way to the fight with Vulcan Raven, you can kill the ravens you see. If you do, Vulcan Raven is pissed when you encounter him.
Depending on the player's decisions, Snake can either enter the top ventilation shaft to first infiltrate the tank hangar building or the bottom ventilation shaft. The decision will be reflected with Master Miller's introductory call, where, if the bottom shaft is chosen, he will explain to Snake about the rodents that Snake is currently following.
Depending on how successfully the player escapes regarding the ketchup or not, the programmers had Snake's response when the player calls Otacon be different regarding the results: If the player fails to escape via the ketchup (either due to not using it at all, or the player wasn't quick in escaping), Snake will coldly refuse to acknowledge Otacon's involvement in the escape. If the player succeeds in escaping via the ketchup, Snake will express some surprise that the trick actually worked.
Despite Johnny's greater cone of vision than the other Genome soldiers in the game, it looks like it would be possible to evade his sight entirely if you hid in one specific corner of the room - so, naturally, the DARPA Chief's body is planted in that corner, preventing the player from using it.
You can make Snake and Raiden... pleasure themselves to the bikini posters scattered throughout the game (and have people on the other end of the Codec comment on it [and have your character comment on their comments]), get your Codec support mad at you for punching hostages or photographing the panties of female hostages, destroy a huge amount of inanimate objects for the time, and get comments from Snake referencing things you won't find out he did until much later during Raiden's story if you call him at the right times.
There's a bucket of ice in the crew's lounge on the tanker. If you shoot it, not only does the ice fly out, it melts realistically; the cubes closer to one another melt slower than the isolated ones.
Also, those ketchup bottles on board the tanker and Strut C of Big Shell? You can shoot at them and cause them to explode, also distracting enemies that way.
There are seagulls on the Big Shell, and killing enough birds as Raiden gets a call from the Colonel and Rose, who chew you out over your animal cruelty. Rose will break up with you and won't let you save until you apologize. Same goes for hitting hostages.
If you chase away the seagulls and then look up in the sky in first-person, the seagulls will crap on you. Also, there are splatters of seagull poop that you can slip on, and there's one pipe covered with it that can cause you to slip off, fall into the water, and drown.
If you enter the only place with a mirror on the Big Shell and equip either the Camera or Sniper Rifle (weapons that force you into first person mode and which you won't have the first time you visit), you see that Raiden is properly rendered holding either.
If you play around with the peeking mechanics in front of that mirror, you'll see Raiden sliding along the ground at lightning speed without any movements other than his breathing. Try it during the boss fight against Fortune and you can, with good timing, actually dodge her railgun shots without actually moving.
There's a point in the game where Raiden is discovered regardless of how good you are, and the whole facility goes onto high alert. If you return (with no purpose in the storyline) to some of the earlier parts of the facility at this point, there are more guards. This is also the only way to get some of the dog tags.
In the Tanker chapter, you get a camera which is important to the mission, but can be used anywhere. It's not surprising that players might try to take photos of things which aren't important to the mission, and photographing posters, hidden characters and female soldiers gets you secret replies from Otacon.
If you take a photo of a poster of a man's chest and arm, Otacon will remark that "that explains a lot."
The box warp returns in the form of a parcel sorting system.
There are two ways you can get a 'Mission Failed' which are highly unlikely in normal gameplay: falling down the lift shaft on Strut A and letting the bomb explode after the battle with Fatman. Both of these have their own specially-created images for the game over screen.
The game takes into account the fact that certain bosses can be defeated in different ways. The cutscene after the Olga fight varies depending on where she was when you shot her, and Fatman is visibly still alive and breathing after the fight if you take him out with a non-lethal weapon.
At one point in the game, you have to find a hostage by calling out to them, with a button command that stops working after the hostage is found. If you then backtrack to the room with a parrot in it, and call out to the parrot enough times (ten or eleven. With no indication that what you're doing is recognized by the game), it learns to say the phrase and adds it into its usual repertoire.
The parrot can also learn to say "Enemy sighted, requesting backup" if you get caught too much in that area.
If you spray the parrot with the coolant it flaps it's wings and says "this sucks."
In the room with the parrot a guard starts looking at pictures of women on the computers.
Plant some C4 in front of sea lice and blow them up while in first person mode: The sea lice will then fly towards the "camera" and splatter against it in a manner similar to insects on windshields of a speeding car.
The player might get the idea to hack the escape from Arsenal Gear's torture room regarding Raiden's... lack of clothing. The developers apparently anticipated this and made absolute sure they didn't model that area, although lines by the guards still imply the presence and the actual size of his manhood.
At Strut C, before talking to Stillman, go into the men's bathroom, stand in front of a urinal, look at it in first-person, and then call the Colonel. The Colonel will tell Rose to give Raiden some privacy, then Raiden begins to urinate and Rose tells him to let her know when he's done.
Going into a toilet stall in the women's bathroom results in a very funny conversation.
It's possible to see Snake in a box on the CD connecting bridge. If you shoot him he gets a ! mark above his head and runs away. If you call him afterwords, Raiden tells him about it. Snake denies knowing anything about it. In a later Codec call about the box, Snake irritably tells Raiden that thanks to him, a couple of his boxes were destroyed.
See that bell on the wall in just one area of the tanker? Shoot it and it dings.
Shoot the pans in the tanker's kitchen and they each play a different note, making a scale if you shoot them in order.
When you are taking Emma across water, Raiden tells her to hear his heart in order to keep calm and not drown. Take some Diazepam, and Emma's oxygen lowers at a slower pace.
In the Tanker chapter, there is a general giving a speech, and there is a countdown to the moment where he finishes the speech. Shoot him with a sleeping dart on the head and the countdown stops until he can continue the speech.
When the general is giving his speech you can screw around with the projectors to make them switch between screens and show pictures of sexy women, which the soldiers turn towards. If you do it too many times in a row, the soldiers figure out something's wrong, turn towards you and catch you.
Soon after you meet Pliskin, if you aim your gun at him when he is sleeping he quickly wakes up, aim his gun at you, and says "I wouldn't do that if I were you." Attack him and he fights back.
You can also attack him later in the game after he gives you the sword. He fights back this time too.
Sniping him during Emma's escort at the water will get you instantly sniped back. Apparently, he's really quick.
If you knock him out at the second time and call him on the codec, he'll be sleeping.
You can anger Emma and Otacon by attacking Emma.
You can also anger Otacon by knocking Emma out and promptly crawling over her body.
You can make the Colonel and Rose upset if you take a picture of a hostage's underwear.
If you aim the directional microphone at Emma at a certain part, you can hear her talking to herself about Raiden. Call her on the codec, and Raiden confronts her about it, and tells her despite her suspicions, his hair is real, not a wig.
You can also listen to Snake wondering out loud if he needs to clear things with Otacon before he asks Emma out.
Try having Raiden cartwheeling up some stairs. He'll trip if they're long enough. Cartwheeling down them is fair game, though, as the cartwheel is the closest to a jump button in these games - rolling as Snake along a staircase in either direction will cause him to trip as well.
The M9's hammer actually changes position when you use it - if you've just equipped it, the hammer will be down, but after firing a shot and chambering the next bullet, the hammer will be cocked.
We're talking about a game series that accounted for the possibility of the player shooting guards in the crotch, and incorporated it into that bit with The Sorrow in MGS3. "I'm useless now!"
We're talking about a series that also accounted for the possibility that the player might have eaten a vulture who had, in turn, eaten human flesh. The victims of Snake's cannibalism-by-proxy also appear in The Sorrow's river, complete with a vulture on their shoulder. ("You ate me!")
You can also find a crocodile cap and peek around corners while crawling, causing guards to believe you are some kind of indoor crocodile and freak out.
Similarly, you might try to use it on the dogs to see their reaction: The dogs will turn tail and flee if you do so.
If Snake gets a stomach ache from eating rotten food, you can cure him with medicine or go to the medical screen, spin him around a dozen times, and then exit the screen and watch Snake puke up, fixing the problem.
It's possible to kill The End just after the cutscene in which he's fully introduced. If you do so, the boss battle is replaced by an encounter with the Ocelot Unit. If you damage but don't kill him after the above cutscene, whatever damage you've dealt to him will still be there when the boss battle actually starts.
Since The End is using tranquilizer rounds instead of regular bullets, getting hit by his shots reduces Snake's stamina gauge instead. If it's depleted, Snake passes out instead of dying and The End carries him off into the basement of a nearby base.
You can also save during The End's boss battle, and leave the console off for a week. This results in him dying of old age. However, waiting less time than that before reloading the save allows The End to catch Snake while he's asleep and carry him off to the location described above.
Calling your Mission Control when you're imprisoned and saving the game has Para-Medic tell Snake about a vampire movie, to which Snake will reveal he fears vampires. Loading the game causes Snake to have a nightmare, which manifests itself as a demo for a scrapped action game called Guy Savage.
During the short period of time you have EVA in your party, so to speak, you can check her medical history. Turns out she has breast implants, she has eaten a Tsuchinoko, andProctitis. Is it possible for Kojima to troll his own series?
This can be seen as Fridge Horror, if you consider that the proctitis is usually in the midst of electrical burns and other wounds caused by the sadistic pervert Depraved BisexualBig Bad. Yep.
Better yet, if you tranquilize her (which significantly slows down her stamina drain), she'll start talking in her sleep about Snake, The Boss and her dog, and makes several sexually suggestive double entendres.
If you harass EVA enough times while you're paired up with her, she kicks you in the crotch hard enough to cause an instakill and a Game Over.
You know the torch you find in the cave? You can use it to set foes on fire.
Also, you might get the idea to use the torch in Groznyj Grad's Underground Tunnel up to arriving at the area to face The Fury. The programmers anticipated this possibility, and added in a few seconds to The Fury's debut cutscene that shows Snake dropping the torch just for that specific scenario.
The torch is only useful in the cave for a short while: if you wander in the darkness long enough, Snake's eyes will get used to it and the area will slowly get brighter and easier to see in.
Shoot or stab Ocelot anywhere on the body without killing him. He will possess a bandage in that spot in all future appearances.
There's a moment during the Virtuous Mission where Ocelot is knocked out on the ground. If you kill Ocelot while he's out cold, you get a Game Over with Colonel Campbell telling you that you created a Time Paradox, and that you shouldn't screw around with the future. The HD re-release even has an achievement called "Problem Solved, Series Over" for doing it.
If you backtrack to areas you previously visited and called EVA there (more specifically in areas such as Dremuchij, Dolinovodno, Ponizovje, and Graniny Gorki, the four places where you can't call EVA upon the first visit due to either being absent [Ponizovje and Graniny Gorki], or hadn't even met yet [Dremuchij and Dolinovodno]), in addition to giving Snake the info about the location he is currently at, EVA will also ask Snake what he's doing all the way back there and remind him that he was supposed to go to the next destination.
Various Codec calls and conversations to characters will also be slightly different depending on the player's prior actions. In Rassvet, for example, Snake's response to Zero in regards to the guard level depends on how the player handles sneaking past the guards. If the player evades detection completely, Snake will respond with "No one spotted me." Likewise, if he gets an alert or kills the soldiers, he'll respond with "I managed to get past them." and "I had to kill them... there was no other way. But no one will know we were involved." Also, call Sigint when the flame troops arrive at Krasnogorje. If the player got a bit too triggerhappy with soldiers, Sigint will state that the reason why they are after Snake is because he killed many of their comrades. Likewise, if the player restrained him/herself from killing anyone (except for maybe the Cobra Unit), Sigint will respond with Volgin sending them to torch him as revenge for disposing of The Pain, The Fear, and The End. In addition, Volgin's analysis on his body check on Snake before torturing him will be different depending on how frequent the player seriously injured him/herself gameplay-wise. If the player had very little, if any, (serious) injuries prior to being tortured, Volgin will state "What a beautiful body you have, like a newborn baby. But not for long..." If the player received a moderate amount of injuries, Volgin will state "Hmm... you've certainly seen your share of battles. Consider yourself lucky. I am about to show you what hell is really like." Lastly, if the player received a lot of injuries, Volgin will say "You're a tough one my friend, a lesser man would be dead by now."
If the player still had the magazine in their possession up to their capture, and then the player calls EVA upon leaving the prison, EVA will mention that she did not throw out any of Snake's equipment, and also reveal that she found out about the magazine, while sarcastically referring to it as a "fine piece of literature" towards an embarrassed Snake.
If you want to preserve the mousetraps you can find in the Virtuous Mission for Operation Snake Eater, set them somewhere easy to find. They'll still be there a week later in-game and you can pick them up.
You might be curious about what happens when wearing the Oyama facepaint and getting caught (and possibly other facepaint). The developers included at least one specific line uttered by the guards when caught (in the Oyama facepaint's case, they'll say "What's with that face?" with some amusement.)
If you leave the transmitter in when you approach the waterfall, Ocelot's soldiers will try to attack you. Also, you get a hilarious bonus cutscene where EVA removes the transmitter.
You can unlock, with some difficulty, the Solar Gun from Boktai. It's very powerful, but difficult and impractical to use due to its limited ammo capacity and the fact that you can only recharge it manually in sunlight. Sunlight, of course, is a stock vampire weakness and the Solar Gun in Boktai kills vampires, so naturally, a player might consider using it on Vamp. He has a special animation and response to the shot (which is almost impossible to land due to how insanely fast he is), and fully-charged it can knock him down him in a single hit. Even better: the Solar Gun is technically a non-lethal weapon. Vamp is the only enemy in the game that can actually be killed by it.
Have Snake die in various ways, continue, and then call Rosemary. Snake (or, in the event that Snake was killed via an explosion, Rosemary) will begin the call stating that he got the feeling that he was killed before in the specific manner in which the player died.
Certain locations in which you can participate in battles between Liquid's PMC forces and local militia change according to how the battle is resolved. You'd usually only spot this by backtracking.
When the ghost of Psycho Mantis tries to vibrate your controller again, the game will note if your controller can vibrate. If so, Mantis will scream, "VIBRATION IS BACK!" If not, he'll be flustered that his mind tactics don't work anymore.
Similarly, if you set the controller to something other than 1 during the battle with Mantis (since the same strategy worked on Psycho Mantis in the original MGS), Snake won't be able to move. Otacon will then call up Snake and tell you that it's not going to work this time.
Shaking the controller when Rose is talking will cause her breasts to jiggle like Jell-O.
If you kill way too many enemies, you will hear Liquid's "You enjoy all the killing!" line from MGS1, and then Snake will throw up. Like the time paradox scene in MGS3's HD remake, accomplishing this after the trophy patch unlocks a trophy by the same name.
There's a couple of joke Dating Sim missions where you can date either Paz or Kaz. Normally, the game prohibits you from taking weapons into the dates, but if you hack the game to allow you to take them, you can kill them. When Kaz fades, his glasses remain and clatter onto the sand.
You can also use the team command "Say Goodnight" and they will...fall asleep. If you lay on top of Paz, she will dreamily state that "your beard hurts" and codec calls from other characters will imply that you are...umm... eating her out. Almost the same thing happens for Kaz, except his line of dialog is "Stop it...I'm not that kind of guy..."
It's more likely they're chatisizing you for taking advantage of someone while they're unconscious.
While the Codec lines in Peace Walker are usually generic or generic for the stage, thus making them hardly worth bothering with for the majority of players, making Big Boss stand on a specific riverbank in a specific stage after recruitment of Huey, the man who will become Otacon's father, leads him to remark that he always gets a bad feeling when he looks out at the water. (Metal Gear Solid 2 revealed that Otacon's father committed suicide by drowning himself.)
The game has two situations prepared depending on how well the CQC quick action cutscene turned out for the player: If the player successfully managed to do the CQC, the player will be able to use the ID card that Snake stole from Strangelove earlier to escape from the cell, although the call with Miller after Snake escapes will be somewhat short. If the player fails, the player can utilize a jigsaw strapped onto him, and after escaping, Miller's codec call will have him reference the Jigsaw.
Given the Sling Post's obvious resemblance to a club or baseball bat, the player might get the idea to smash it into enemies. The game programmed it for that specific purpose, and doing so will also activate a codec call where Miller will commment that it's not what its supposed to be used for.
Try shooting the ! above a guard's head if you're discovered. It stuns them momentarily.
If the player shoots the soldiers in the butt or in the crotch, it will instantly knock them out.