One of the interesting new additions to the DualShock controller for PS4 is the light bar. Coupled with a new PlayStation Eye camera, the light bar will enable some PlayStation Move-esque functionality. (It will make co-op games smarter, as well.) However, there are other applications for the light bar, as evidenced by Killzone: Shadow Fall.
"The light-bar doesn't require the camera to function," Sony's Shuhei Yoshida explained to Edge. Even when uncoupled from a camera, the LED screen will allow players to quickly identify which controller is theirs. Also, "game designers could use it for some effect," Yoshida said.
"Like when [players are] losing HP, the color could change from green to red. Like in the Killzone demo, if you were watching Steven playing, [that game] has that function already," he pointed out. "People were watching the main screen, but Steven was facing the audience, showing how the light bar color changes as he was hit by the enemy; as he lost hit points the color was changing from green to red. And when he used the health replenishment, it went back to green."
Some PlayStation Move games took advantage of the colored orb as well. For example, in Sorcery, the orb changes color based on what spell you have selected. However, with PS4, every game will be able to offer additional information through the light bar.