You'll finally confront Dr. Breen in his office at the top of the Citadel. He's attempting to escape through a portal. Your objective is to prevent his escape and destroy the Dark Energy Reactor. Breen himself is not a direct combatant, but he's protected by Combine forces and the environment. Alyx Vance will assist you in this final battle. She'll provide crucial information and help you target the reactor's weak points. The room is filled with energy conduits and Combine technology that you can manipulate with your supercharged Gravity Gun.
Half-Life 2
Confrontation with Dr. Breen
Confront Dr. Breen in Half-Life 2's Citadel. Prevent his escape, destroy the Dark Energy Reactor, and use your supercharged Gravity Gun with Alyx's help.