According to his blog, Jonathan Blow stated that he wanted to see genuine responses by attendees to the game without providing any hints about what the game was or who was behind the title.
The game was sitting by itself between the Monaco and Retro/Grade booths. It had no information regarding what the game was, and while Blow was around the booth examining results, nobody was there to tend the booth itself. All the booth had was a monitor and the game running.
A few game developers and news people, including Steven Totilo from Kotaku, noticed the game in the middle of nowhere, but they were told to keep it on the down-low. In the end, Blow said the game did not fail and kept certain attendees' attention for quite a while. Now he has to worry about finishing the final product!
I had several reasons for wanting to show the game this way. Firstly: At a show full of companies trying to capture your attention and sell you things, I wanted to do something that is subtle, and a surprise — if you notice it, and decide to investigate, you find something unexpected.
Also, I wanted people to be able to play the game for as long as they want, not feeling pressured to stop playing because of a huge line of antsy people waiting behind them.
The Witness is the newest game from Jonathan Blow, the developer behind the smash-hit puzzle-platformer Braid. The Witness is an exploration-based puzzle game based in an otherwise uninhabited island. It is promising to use an artistic lighting engine that literally paints the textures onto each object within the game. It is expected for release for multiple platforms in late 2011.
SOURCE: The Witness Dev Blog