It was from half life 2 episode 1  
Explanation why the gravity gun became blue supercharged
 
When exposed to the Confiscation Field in the Citadel, the Gravity Gun is “supercharged” rather than being vaporized as other weapons are. It also shorts out the field in the process. Once supercharged, the Gravity Gun emits blue light rather than orange, quakes in Gordon’s hands, and creates small bolts of energy across its muzzle. Its powers are vastly enhanced, enabling it to manipulate objects of far greater mass than it normally could as well as pull and repel them with greater force. Its most significant enhancement, however, is its ability to manipulate organic matter.