Inside is the best Xbox One game I have played thus far. Developer Playdead Entertainment's follow-up to Limbo, Inside is worthy of every bit of success its predecessor received, if not more. Similarly bleak but with a great deal more polish than Playdead's previous ultra popular indie game, there's a great deal to parse as Inside's end credits start rolling, from the myriad of strange events you'll witness during your playthrough to its head-scratching finale.
With that being said, we're going to go heavy on the spoilers here (seriously, if you haven't played Inside yet but plan to do so in the future, I advise you to stop reading this) and take a closer look at the game, its ending and what it all means. While there's no set confirmation from Playdead in regards to the game's story, this is a pretty watertight theory, even if I do say so myself. Let's press on, shall we?
The secret ending suggests the boy is being controlled, too
Inside will see the player-character take control of a number of zombified, brain dead humans, with him able to move them along a level using mind control. However, the secret ending for the game drops a strong, almost bulletproof hint that he is a mindless zombie, too.
The secret ending can be revealed by first finding all of the hidden orbs scattered throughout the game, with you then able to return to the cornfield segment near the beginning of your journey, clambering into a hidden vault tucked away beneath the ground. After entering a musical code, you then venture through a tunnel that eventually leads to a room with a mind control helmet and a switch. Unlike the other helmets in the game this one is connected to the floor, with it shutting down when the boy flicks the switch, simultaneously causing the boy to become motionless and thus ending the game.
So what does this mean? Well, considering that the boy's stance following his flicking of the switch mimics those of the zombies when they are disconnected from a mind control machine, this seems to suggest that Inside is breaking the fourth wall here and pointing out how you are in control of the boy. When you turn off the switch, you are effectively cutting off the mind control connection between you and the player-character, therefore ending the game. This suggests that the boy hasn't been fighting towards the end of the game of his own volition, but rather because you have commanded him to do so.
However, there is another equally - if not more - convincing theory regarding the effects of the switch, but we'll get to that later. You can watch the secret ending below: