Not to bring a dead discussion back from the grave, but I have to reply. TLDR - The IT can go either way.
Shepard is suffering PTSD. The shadows are not exclusive to indoctrination.
Oho, but they probably are for ME. There is a conversation you have with the Rachni Queen in ME 1 through the body of an Asari and during it, she explains that whilst she and her young were under the attacks of indoctrination by the Reapers during their last visit, she claimed to see "oily black shadows" while sleeping. The very same entities that appear in Shepard's dreams in ME3.
Seeing as how something that specific is explained and visual seen, I'll go with them being attempts of indoctrination on Shepard. PTSD works too if you want it to.
Ashley/Kaiden armour visual style is used to represent common generic human troops. They're repeated because the corpses are a simple repeated asset.
Except that common generic group hasn't been used since ME1. Why are they showing up now at the end of ME3? And why are they all scalped?? (irrelevant, but why?) And how in the hell did all of those bodies magically appear there? After Shepard wakes up after Harbinger's beam, he can clearly see Harbinger flying away. So Shepard hadn't been knocked out for too long. A couple of minutes max. He get's up and there are hundreds of soldiers that coincidentally all happen to be wearing outdated gear piled-up-dead on the sides? How can Bioware have screwed "this" up? They deliberately modeled them to look like ME1 soldiers and deliberately placed an absurd amount of them there in a short period of time. (they are supposed to be a visual representation of either a dead Kaiden or Ashley. your choice on Virmire in ME1)
Both continuity error. Not the first in the saga.
Ok, fair enough, but man oh man, I still have trouble accepting how that kid got from one building to the next that fast.
Because BioWare. Because they wanted to give a hint that Shepard lives, and to get people talking. Lots of speculation from everyone.
Ok, fair enough, but pretty devious of them to include only one 20 second secret movie at the end of the ending that just so happens to line up with the indoctrination theory.
It's nice to want things. Again, almost all of these arguments have the prerequisite that BioWare's narrative structure is perfect and they made no errors during the telling of this narrative and development of the game. This is a confirmation bias.
You maybe right and I'm glad there are people like you out there who constantly fight for their side. I really try not to be bias, but I still can't shake the feeling that the IT is a real thing or at least something that someone from Bioware will finally acknowledge was deliberate. From the pieces of evidences that seem undeniable to me, all the way to the tweeted answers from people who work at Bioware, winking and saying "Maybe" or "You never know" at questions to the IT. Yup, I still can't shake the feeling.
Because Bioware is incompetent. Why would you make up this elaborate theory when the obvious and only logical explanation is that Bioware just didn't think of that but wanted to have Shepard interact with the kid once then see him get killed as he's leaving earth, with the kid being intended to symbolize the suffering on earth and so on. Do you really think every part of the Mass Effect trilogy is so deliberate that they took everything into account? If you start thinking like that, you could poke a million holes into the whole thing.
Well, "I" didn't make up the theory. I found out about it in the second doc. And you know what? You could be right. Maybe the "only" logical explanation is that Bioware IS incompetent and the whole story with the kid in the beginning was lazily done. Or maybe, as I stated with EatCheese earlier, that something happened near the end of their development and things needed to be changed, so they added in all of these trails that ultimately lead to the IT. No one knows for a fact, right? So it could go either way.
Do you know what kind of ending BioWare planned before ME3? Dark Energy/Element Zero, the sun "Dholen", the human Reaper/human DNA... everything was scrapped before they started developing ME3, so there was never the intention to create an ending like the one described in those IT videos.
Yes, Shepard was supposed to be indoctrinated, but that was another mechanic. Much simpler than you might think -> "you're regaining control"; "you're losing control" which would lead to a boss fight with TIM (which didn't happen because BioWare couldn't implement the right gameplay mechanics). So where are design docs for the indoctrination theory? It's simply a messed up and often reworked ending.
Yes, I'd read a bit about the several ideas, but just because for whatever reason those were tossed out, how do you know the IT wasn't fully intended at some point? I'd love to get these design docs on the IT, but Bioware won't say as much as a peep about them. And I'm sure there are many other things they refuse to comment on regarding the other ending(s) as well.