These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternate Character Interpretation: The black block (the only thing in the game that you could tentatively call a character) is pretty creepy, so it's easy to think of it as an antagonist, a tease, an Eldritch Abomination, etc. But you could also interpret it as just...lost. It seems to be trying to find its way home. This also gives us an alternate interpretation of the player's role — instead of just being "the player", you're a hero of sorts. This poor black block can't find its way home, and you swoop in to save the day and personally escort it back to its proper place. With this in mind, the Gainax Ending can feel like a Crowning Moment of Heartwarming.
Award Snub: Despite all the press and praise early in 2013, by the time the end of the year rolled around this game had been largely forgotten by critics on "Best Games of the Year" lists.
Captain Obvious Aesop: The quotes you find scattered throughout are intended to be both clues and musings on the nature of life (see the game's original title). Many find them more useful as the former than the latter.
Disappointing Last Level: While the game was very well received overall, some critics noticed that the game started to tone down the Mind Screw it did so well in favor of more standard Block Puzzle mechanics as you upgraded the block gun.
Fridge Brilliance: "Failing Forward" starts with one of the most Guide Dang It puzzles in the whole game. There's a pit with a small bridge over it that's too short to help you cross it. If you jump, you'll just fall to the bottom. Players will just pick some blocks down there and use them as an elevator to reach to the other side. However, if you don't and instead press the Escape button and come back to the same room, you'll see the bridge is now a little longer. Repeat this, and eventually the bridge will be long enough to cross the pit. You'll now be wondering "How on hell did the creator expect me to figure that? And then you'll see the sign at the other side: "You can't do everything yourself". He didn't. The creator apparently assumes most players won't learn of the bridge solution unless they heard of it somewhere on the web, and is basically saying "OK, there's nothing wrong with looking for help if you really need it, there are things we just won't be able to do by ourselves" (mind you, there's still the block elevator solution, so you can still complete the puzzle on your own, you just won't learn of the other way).
Game Breaker: The Red Gun's ability to turn as little as two cubes into a theoretically infinite number of cubes trivializes all of the puzzles that weren't specifically made with it in mind. Depending on how well you know the layout, this can be a lot of puzzles.
The ending may qualify. As soon as you capture the black block, the game loses all color and the ambient soundtrack becomes dark and ominous, with the constant rumble of thunder being heard in the background. And if that wasn't enough, once you shoot the black block into a wreckage inside a dome, it rises up and forms the Antichamber logo, which starts sucking everything in like a black hole, including itself. After that, the credits roll... and then the game closes itself.
The DON'T LOOK DOWN room. Take the Schmuck Bait, and you see a giant eye appears on the floor. It blinks, the floor disappears, and the player is forced to plummet down a lengthy shaft while the usual ambient sound changes to a thunderstorm.
Scrappy Level: Stairway to Heaven, ironically, is one of the rooms you'll end up hating the most; not because of its difficulty, but because many different puzzles around the game lead to it (it's quite the inverse of a Hub Level: it has a lot of different entries, but not many exits). It can be very frustrating to solve a puzzle believing you're going to unlock a new zone, only to discover you're again in the same room where you've already been lots of times. Worse yet, once you've seen the room's glowing balls, and therefore realised where you're now, it's too late to go back: the passage you came from has already disappeared, meaning you have to use the Escape button to come back there.