Metal Gear Solid 4: Guns of the Patriots

When entering the password into Otacon's terminal, input 14983. Although incorrect, Snake will (invisibly) gain 100K of Drebin points. Run through the game a few more times with this and the no kills and no alerts bonuses, and you should amass quite a sum of Drebin points.

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

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.

Equip 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.

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

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

In Act 4, kill one of the wolves after you defeat Crying Wolf. The others 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.

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").

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

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