The Pixel Cloud is exactly how is sounds. It is a cloud of pixels ranging from black to gray in color. It flies around ominously in multiple levels, threatening the AI's.
The Pixel Cloud "eats" AI's and the eaten AIs are sent to a confined section of the matrix and they no longer have a chance to escape the realm. It ate many of the AI's that were with Laura, an AI who was trying to escape the matrix, before she met with Chris, another AI who developed feelings for Laura. It eventually flies around and eats Thomas, the protagonist, along with Laura, Chris and the others.
The Pixel Cloud does not seem to be restricted by any normal means, like the other characters in the game. It is able to pass through, behind or in front of walls that an ordinary character could not. It also has the ability to fly around as it pleases. It most noteable ability is how it "eats" rogue AI's and sends them to a confinement where escape is nearly impossible.
- The Pixel Cloud eventually proves useful when it eats the AI who betrayed the others, Grey.