Below are some miscellaneous secrets, tips, and Easter eggs to enjoy while playing through Metal Gear Solid 4. Note that these will include some game play and story spoilers so you may want to read this section only after you have completed the game.

• If you’re watching a cut scene and Snake’s psyche drops suddenly, press "X" repeatedly while it’s still onscreen and you can replenish the psyche.

• After meeting Drebin you’re able to purchase weapons, ammo, and items. On Wednesday and Sunday you receive a 20% discount. You don’t have to wait until Wednesday or Sunday: just change the date on your PlayStation 3!

• Shaking a Sixaxis controller will return Snake to the standard OctoCamo. It also works during cut scenes!

• During the mission briefings once the screen splits you can control Metal Gear Mk II. Explore! You’ll find various items and can even gather hidden FaceCamo. We describe all of these during the walk-through. Search upstairs to find batteries (and down near the helicopter) and iPod tracks. Grab a camera near Sunny’s desk. And bump into Otacon, Naomi, Sunny, and Roy Campbell to obtain unique FaceCamo (after defeating Laughing Octopus).

• Grab the camera using Metal Gear Mk II during the mission briefings (look near Sunny’s desk). When you battle a beauty, just avoid her for about three minutes and you will enter a white world. Use the camera and point it at the beauty for some unique photography opportunities. Try playing the iPod track Oishii Chuhan Seikatsu.

• Completing the game unlocks several new combat vest colours as well as the Boss Extreme difficulty level. You can also purchase new emotion ammunition and coloured smoke grenades from Drebin on a new play-through.

• During game-play load "Oishii Chuhan Seikatsu" into your iPod and give it play. Pause the game and check the camera in the Nomad. You’ll probably spot Sunny enjoying the music!

• There are some secret codes you can enter into the control panel in Otacon’s office in Act 4. Use 14893 (Drebin’s codec frequency) for 100,000 DP; type in 78925 and 13462 for iPod tracks.

• Sunny’s eggs come from caged chickens on the Nomad. You may have noticed the three chickens’ names during the cut scenes: Solid, Liquid, and Solidus.

• When you reach South America: Research Lab, there are a couple secret scenes during the opening cut scene. Hold L1 as Naomi sits on the bed and watch Snake attempt a sly maneuver. Also, later after you save the game she’ll crouch in front of you after delivering bad news. Hold L1 for another secret scene and Snake trying to catch another glimpse.

• Obtain the Sorrow Doll from Screaming Mantis in Act 5. Do so by shooting it out of her hand after you have shot the Mantis Doll out of her hand. Keep it for another playthrough and equip it during your exploration of Shadow Moses. Use the camera and you will spot strange apparitions throughout the act.

• In the level South America: Mountain Trail during Act 2, reached a river area, walk over to the northern side and spot a circular clearing in the grass. Stand in the centre of this clearing and you will receive a familiar audio flashback from veterans of the Metal Gear Solid series. After the transmission concludes, you receive a DP bonus.

• Although the Act 5 Mission Briefing doesn’t take place on the Nomad, there’s still some fun to be had with the Metal Gear Mk. III. You can’t move him around and hunt for items but you can move around the projection screen. Give it a shot!

• When you’re inside the Vista Mansion bedroom, stand on the bed and look up. There’s a poster above the bed! Apparently the guy who slept in the room was a fan of Akina Minami. Aim your weapon at the poster and look in first-person mode and Snake will say "It’s Akina!" while his psyche rises at a hyper-increased rate. Apparently Snake is a fan as well!

• When you start a new game and are watching the unusual television programs, you can change channels using the "X" button. One of the programs features the man behind Snake’s voice, David Hayter.

• If you aren’t able to collect the bandanna (no kills) or stealth camouflage (no alerts) during a play-through then you can purchase these items from Drebin on a subsequent play-through. Unfortunately he charges 5,000,000 DP for each item. Well, that’s only 4,000,000 on Wednesdays and Sundays! Or only 2,500,000 during Act 5!

• If you die during the game, choose to "continue" instead of reloading a saved game. Do this a few times and then give Rosemary a call for a unique codec conversation about Snake’s dreams of death.

• During the boss battle with Screaming Mantis, switch your controller assignment from "1" to "2" for an amusing codec from Otacon. If you don’t do anything at the beginning of the fight you will receive another couple amusing calls from Campbell and Rosemary.

• Get to the Heliport in Shadow Moses and find the Mk. 23 underneath the vehicle in front of the tank hanger. Aim and point the Mk. 23 in first-person mode and listen to Snake. You receive a bonus 1,000 DP. Also, maneuver the camera for an overhead view, similar to the overhead view in Metal Gear Solid, for another Snake-ism: "Overhead view, now that’s more like it!" You also get another 1,000 DP.

• The Metal Gear Mk II and III should be familiar to fans of another one of Hideo Kojima’s lesser known but equally classic games, Snatcher.

• When Raiden and Vamp are fighting on top of Metal Gear Rex while Snake fights off the self-destructing Gekko with the rail gun, aim and fire the rail gun at Raiden and Vamp. Snake will refuse invoking a similar situation in a previous game.

• If you have a Sixaxis controller, call Rosemary at any point during the game and start shaking your controller. You may notice something else on screen "shaking" around.

• Find the first statue in the Middle East: Red Zone during Act 1 and get on top of it. When you press "triangle" Snake will strike a pose and go undercover as part of the statue. Try pressing "triangle" repeatedly and watch what happens.

• During Act 1 you will find dumpsters (you’ll also find more later, such as in Act 3), which Snake can hide inside. While inside a dumpster, give Otacon a call for an amusing conversation.

• After the Screaming Mantis battle and the encounter with Psycho Mantis, wait until Psycho Mantis explodes and press "X" for a secret "Hideo" flashback.

• When a character is introduced and the voice actor’s name is revealed, hold down R2 and it will reveal the motion capture actor instead.

• During the Act 1 Mission Briefing pilot Metal Gear Mk II upstairs. Look on the table next to the radio and discover that Sunny has her very own PlayStation 3. During the Act 2 Mission Briefing, pilot Metal Gear Mk II upstairs and wait for Sunny to return after Otacon begins Naomi’s message. Sunny begins to unpack a box that contains her very own PSP! Check out the game she’s playing. It’s Penguin Adventure, one of Hideo Kojima’s first titles.

• After completing the battle against Crying Wolf and Crying Beauty in Act 4, kill all of the wolves left behind. With all the wolves dead, give Otacon and Rosemary a call and listen to their reactions.

• Pause the game and go to the camouflage screen. Select the viewer and spin Snake in a circle using the analogue stick. Just keep spinning! After a minute, exit and return to the game. Apparently all that spinning got Snake a little sick!

• When you begin Act 3 and the resistance member first appears, put on the Civilian Disguise with the Laughing Beauty FaceCamo (if you acquired it). Approach the resistance member slowly. Hearts appear above his head—apparently he’s in love!