For the person who took up the demo after me, it was about moving forward as quickly he could, attempting to adhere to an entirely pointless 90-minute time limit while ignoring all the lessons the game had to teach. Here's the thing: I'm not entirely sure either of us was playing it wrong.
There are a lot of heady concepts at play in Antichamber -- things like perception, Pavlovian response, psychological conditioning, impossible objects and spacial distortions. It's a menagerie of phenomena that focuses on imbuing you with certain expectations about how the world around you operates, then changing those operations without warning, standing idly by as it waits to see how you react.
Take, for instance, the very first puzzle: The player stands in front of a chasm, and is told by a word scrawled into the environment to "Jump!" If you walk across the pit, a bridge forms beneath you, allowing you to safely cross. If you follow the instructions presented to you, you'll plummet to ... another platform, standing in front of yet another chasm. Lesson one: This world lies to you with no hesitation.
But it doesn't always lie to you. Its puzzles are designed to teach, not to deceive. The second chasm doesn't provide you with any instruction, leading me (and the player who followed) to cautiously walk across the invisible bridge. Halfway across, though, we came to an impeding chest-high wall. My initial reaction was to jump over it, but remembering the rules established by the last puzzle, I simply walked around the space until I found a gap I could travel through.
The gentleman who followed simply jumped over the wall -- as we've been conditioned to do since the beginning of the platforming genre -- and plummeted down, down to yet another level of purgatory; but not to his death. There's no death in Antichamber, only failure, which can be reversed by teleporting back to your central hub and trying the failed puzzle over again.
The player who followed doubled back, and after a few minutes of watching him second-guess his decision, I could no longer watch. He might still be in there.
At one point, I found a gun that allowed me to manipulate certain blocks in the environment, which I used to activate switches, hold open doors and create my own stair-steps to scale tall walls. These exercises were layered on top of me with lesson after lesson until my mind was buzzing with options every time I encountered a new puzzle. I spent a few minutes wildly overthinking one such puzzle before I realized the solution was as simple as hitting a switch, and walking through a door. Again, my expectations were defied.
Antichamber approaches trickery in this respect, but never reaches it. After being outmaneuvered by a puzzle (to the silent jeers of my onlookers), I understood exactly what I had done incorrectly, and what new piece of information I now possessed that I could wield in future puzzles.
I suppose all games, in some form or another, want you to learn their unique languages and rulesets as you pursue total mastery over them. That pursuit has never been so pure as it is in Antichamber, where "mastery" is an impossible goal due to the frequent mutations the game's rules take on. Perhaps that's what set Antichamber apart in my mind as one of the standout titles I saw at PAX. It's one of those rare puzzle games where it's not about how much you know, but rather, how much you think.