This game is BUILT on fridge brilliance, especially when it concerns the Origami Killer's identity: at first, you think the killer is a character who's actually not associated with the main characters, since all of them have a motivation to look for his identity; then it makes you suspect Ethan is the killer because of his blackouts and recurrent nightmares of drowning bodies, pointing to him not being in control of his actions and having visions associated with the killer's M.O.; then Shelby's investigation of Gordi Kramer makes you believe he's the killer (especially after you meet him); then, Madison and Shelby's lines of investigation lead you to (correctly) think that the deceased John Sheppard's brother is the killer, and you're in a 50/50 on whether the killer's Ethan or Kramer; THEN, the attempt on Shelby and Lauren's life makes you think Kramer's DEFINITELY the killer; THEN the meeting with Kramer's father disproves Kramer as the killer and suspicion goes back to Ethan; THEEEEEN Jayden's investigation reveals the killer has links to the police force, and suddenly all the evidence so far starts REALLY pointing at Lieutenant Blake; FINALLY, it's revealed that Scott Shelby (formerly Scott SHEPPARD, formerly a cop) was the killer all along, that his investigation was just a cover to get rid of all evidence of his crimes and to look for his copycat killer, and that all the clues where right there staring you in the face as to his identity.
It's likely that Scott Shelby merely uses his childhood trauma as an excuse to satisfy his urges, considering that in the end, he intended to shoot Ethan even after he had succeeded in the trials.
It is hard to tell for sure, especially considering that another ending has Shelby let Ethan shoot him after rescuing his son. Is he a death seeker as well? Perhaps all of the above?
Maybe it's Shelby wanting to die on his own terms: gunned down by a father willing to do whatever it took to save his son. When his identity is revealed, the situation changes, and he is forced to kill anyone that knows who he is to continue the game.
You might have complained at how HARD some of the controls become in the more tense moments of the game. Then you realize: the controls are hard because the situation ITSELF is hard. The anxiety and fear the characters are experiencing reflects in how hard it is for you to make them fulfill a task.
Also, note the "Four Heroes" trophy for the game. The only one who doesn't need to be alive at the end of the game is the most conflicted character of all, our Ensemble Darkhorse Shelby.
Most, if not all of Scott's thoughts, listened to on subsequent playthroughs, tend to lend themselves to this. From hearing how he thinks out his actions in Manfred's shop to him noting that he hasn't been sleeping well since the murders started up again. Many of his thoughts hold a double meaning, having been worded by the writers just vaguely enough to work for unspoiled first time players and those who have knowledge of The Reveal.
You know that case Shelby claimed to investigate? It was indeed a case: The identity of his own copy-cat.
Jayden's Butler cryptically warns him that "Too much reliance on 'you-know-what' could be dangerous." At the first incident, the player is lead to believe that he means Jayden's drug of choice, Triptocaine. But oddly, Jayden's withdrawal in the hotel keeps dragging him back to the ARI simulation...
If you notice, every single one of Jayden's withdrawal moments happen right after he uses ARI.
And something little: during "Solving the Puzzle", in which you can die from ARI overdose, the weather in the pleasant fall environment gets progressively worse, until it's thundering and lightning. A nice touch.
If you compare the way Ethan and Jayden commit some of the same actions of the game, it really accents how much of a normal yet unfortunate guy Ethan is. Ethan holds the gun he uses in the Shark Trial and potentially against Scott completely wrong, whereas Jayden has a perfect grip and stance. Also, If Jayden gives CPR to Shaun, he does it properly by plugging Shaun's nose and tilting his chin back, whereas Ethan doesn't.
Captain Perry can't tie his own tie because police wear clip-ons so that they can't be choked with their ties in a fight.
Scott Shelby has been hired by the families of the victims of the Origami Killer to investigate. But since he's talking WITH the families of the victims of the Origami Killer, who hired him? Exactly.
After Shelby drops in on Kramer's house during Face to Face, Kramer explained he was just trying to protect his son Gordi, who he said he'd love no matter what he did (including murder) and would do anything to protect even if it meant killing others, Shelby almost walks away without harming Kramer any further. After all, Kramer basically said he was willing to suffer to save his son. Shelby only roughs him up more after he screws it up and says no one would miss Gordi's victim anyway. Bad move.
Why did the (then) mystery brother have so much trouble keeping up with John in the flashback scene? Because he was asthmatic, of course.
Here's a better question: why are we even controlling the mysterious brother in the first place when there are only supposed to be four playable characters?
Shelby had a police badge in his desk, but is retired from the force. One would think that any police agency would require retiring agents to return their official identification and/or credentials.
And then there's the fact that if you do well in Scott's first few chapters and get the box from Hassan and the cell phone from the suicidal mother, he doesn't even mention either piece of evidence to Lauren. In fact, neither are brought up at all until he burns the evidence near the end of the game.
Early in the game, when Shelby speaks to Hassan, he has the option of mentioning Shaun's disappearance...despite the fact that Shaun had only been reported missing earlier that evening, nothing was reported in the media about it at that time, and there was no indication that Ethan ever approached Shelby for help.
Hell, there's the whole fact that after a while, it seems that every section involving Ethan, Jayden, or Madison unearths more and more about the nature of the killer, while Shelby's chapters... don't. Very odd for a private investigator and former cop to seem so ineffectual. The only time he does succeed at anything is when it's at the behest of Lauren.
And most of Scott's lines. For example, in Hassan's shop, while asking about Hassan's son, Scott says "I once lost someone close to me...".
One of Shelby's internal thoughts in Manfred's shop; "Lauren really believes she's onto something. I think she's going to be disappointed."
And while the face-to-face scene was really awesome, there's still a massive pang that makes you feel like this is really out of character. Scott Shelby seemed like such a nice guy up until that point. How could he have murdered fifteen people without breaking a sweat...?
Oedipus Complex: Tied into, appropriately enough, Shelby's Freudian Excuse. We have a man whose brother drowned because of a drunken father refusing to save him. This causes his mother to lose custody of him, and she puts him up for adoption. So, fast forward a few dozen years later, and the Origami Killer starts drowning little boys in rainwater while putting their fathers through hell trying to save them. In addition, Shelby saves the mother of one of his victims from committing suicide, and even steals a kiss from Lauren depending on how the player plays it. So, if we accept that Shelby's victims are like his surrogate drowning brother, then we have a man who is vicariously punishing and likely killing his surrogate father and stealing a kiss from one of his surrogate mothers. So....yeah...
Why is Shelby such a hero? He isn't. All the people he protects when they're in danger are the surviving parents of his victims; he's saving them because he still needs them to tell him what they know, or turn over any evidence they may have left. The times he can just go ahead and leave them to their fate are the ones who wouldn't cooperate with him. Walking away from Lauren's apartment takes on a really sinister note if you already know who the killer is.
Hassan in particular can take an even crueler twist since he's the only one you can leave to die during questioning (Lauren's death doesn't come until much later in the game.) This can be due to the fact that Hassan, who is in good health, did not do the trials.
It's implied that Norman Jayden is addicted to Tripocaine, the blue powder he snorts whenever he has withdrawal attacks, but after replaying the game a second time, I got an epilogue where Jayden begins hallucinating objects from inside his Augmented Reality environment without his glasses on. Then it hits me: The ambiguous "It" that his software agent Valet keeps telling him not to overdose on is the Augmented Reality. His 'withdrawl' symptoms always set in after he uses it for an extended period of time. The blue powder is a treatment for the effects ARI has on his body, since it always makes the twitching, nosebleeds and other symptoms go away.
It is, however, still a potentially deadly drug. Another epilogue shows Jayden overdosing on Triptocaine. So while the Triptocaine helps counter the effects of ARI on his mind, it still has consequences for his body.
One must consider the other possibilies though. In this specific ending Norman is looking for a refuge. Combining the assumption that ARI is detrimental to the user's health AND that he has grown rather fond of using it often (Remember his pretty high score in a game where you throw a ball against a virtual wall) it seems like, that he is using ARI as said refuge. The ending mentioned in the first paragraph already clearly showed that using ARI messes with one's mind and that Tripto's purpose is to supress the side effects. I can imagine that Norman, in this state, spends a very long time in ARI only to pop some Tripto when he can't take it anymore. So it might as well just be, that it effectively was ARI that killed him, maybe because he wasn't able to take any more Tripto or because it didn't work anymore (drug tolerance?)
To support (if not flat out confirm) that ARI is indeed what the waiter is warning Jayden about, a scene plays if you take far too long trying to piece together the evidence in the last ARI scene with Jayden where he dies from it's effects. His eyes start to bleed (as evidenced by streaks appearing from under his shades) and then a cutscene plays where his nose starts bleeding as he flails around in ARI, finally collapsing dead on the desk. No Triptocaine is used through these events, ruling that out (and considering he's fine if you do solve it, It's not the Triptocaine he took earlier.)
As far as I know, Triptocaine; as a device to counteract the affects of ARI is - fanon. It's entirely possible that the drug and the device, work in tandem, or are equally dangerous. The fact that tripto comes in a glowing blue vile, and it's invention (existence) is as much a headscratcher to the audience as ARI, they may have been spawned for similar reasons, by the same source. Which could also explain why Jayden is comfortable working with an addiction - if the actual work itself is responsible, somehow.
It's possible for Norman Jayden to accuse Carter Blake of being the Origami Killer. It's not him, of course, and Norman doesn't have sufficient proof. But there's also another reason it can't be Blake: Blake doesn't fit the profile of the killer Norman put together earlier because Blake is impulsive, and the killer is a meticulous planner, and Blake is such a jerk that he makes everything personal, while the Origami Killer has nothing against the victims.
Probably one of the biggest giveaways you realize once you complete the game; Shelby says he's a private investigator looking for the Origami killer, but he never once actually tries to make contact with Ethan, the father of the current victim. Becomes even more noticeable when Ethan becomes one of the prime suspects later in the game.
The death of John Sheppard. As pointed out in other places, if he had simply fallen into the hole, he would have been swept away, so he would have needed to climb into the hole to get stuck the way he did. This is pretty stupid, but remember that immediately before this the kid was running around a construction site, recklessly doing a ton of things that could have gotten him killed or injured, and not really giving it a second thought. Being Too Dumb to Live might have actually been intended characterization.
In a weird way it gives John a parallel to Jason, too. If Too Dumb to Live had an official T-shirt, Jason's face would be on it. Not to mention it gives Shelby and Ethan a connection, since both of them tried to save their respective loved ones from terminal stupid and failed.
About a quarter of the way through the game, you figure out what that little number under the date and time means...
If you have Ethan follow the OK's instructions during the Shark trial, imagine Sarah and little Cindy coming home from school, wondering why the house is such a mess and why daddy doesn't seem to be in, before going to their room to play.
In "The Doc" chapter, if you have Madison do the smart thing and leave the house after she gets her clue, then Adrian Baker will still be around to continue murdering people horrifically in his basement.
At a few points in the game the player can let Scott Shelby drink (such as at the bar during the party level) and its been shown that he keeps a bottle of booze in his desk drawer. The implications of this is that he is at least a moderate drinker. Guess its something he picked up from his father.
There is a heartwarming scene near the beginning of the game where you help the mother of one of the Origami Killer's victims after she attempts suicide. While she is recovering, you can choose to take care of her infant daughter, Emily. Isn't that sweet? Turns out that the character you are playing during this scene is the killer.
Two out of Three of the victim's families you meet during the game are single mothers who's husbands mysteriously disappeared not long after their sons. During one of the trials, Ethan can find the corpse of a father who previously attempted the trial. No doubt these "missing fathers" died during their own trials.
Once Shaun's rescued, he'll comment that he knew his dad would come save him. It can be hard not to wonder how many other boys thought the exact same thing, and ended up being wrong.