Brains are Project Spark' s approach to visual programming and are essentially a series of code that gives tasks, functions, variations and properties to all in-game props. By assigning commands through the brain editor, the player is able to program the prop through a series of visually represented choices. The first example was demonstrated at E3 2013 by modifying the behaviour of a rock, which went from having an empty brain (no code assignment) to following the player upon detection. A thorough list of assignments is found in the "categories" section of this page.
As well as having the ability to add brains to things that have no brains, the user will also be able to edit brains of existing entities, including the playable character. Some things have pre-built intelligence based on what you would expect that entity to do, for example, Goblins attack you and birds fly away, but there is no restriction on changing these completely, you can change a Goblin from aggressive, to passive, to friendly, to acting like a bird himself and flying away, the possibilities again, seem limitless. Changing the brain of the playable character enables you to completely modify the gaming experience, from changing which button makes you jump and how the camera works to what your character can actually do.
The code system that Brains use will substitute typical complex coding terms for the phrases "When" and "Do". So while programing a brain, players can say WHEN all of the conditions are met, then DO this. For example, someone could enter, WHEN a player presses the A button, DO jump. A player can also make that program more advanced by saying, WHEN player presses the A button, AND the player is on the ground. DO jump 2 feet above the ground.
Brain properties can also be modified by going to a prop > edit > properties > brain