Begin a new game on the Insane difficulty setting and play through the Prologue area until you destroy the Comms Tower, partway through. Blast the bunker with grenades, and grab a new set of grenades to make the next area easier. Open the door, proceed to the main gate, and initiate a cutscene by interacting with the panel. Keep going to the next area. As you come through the gate, you should find three enemies. Kill them and then sprint toward the stairs. Before you reach them, however, turn toward the right. You should see a gate starting to close. Dive under it before it is done closing and you will find a container to your left. It contains a special freeze ray weapon that should remind you of the one used in the Despicable Me cartoon, although it unfortunately doesn't come with enough ammunition to be especially useful throughout the remainder of the game.