In certain levels you have grenades or grenade launchers.
Three launched at far range or one at close range will kill them.
If they do not die, pull out a gun. When the auto aim is red,
it indicates near death; you can easily take them in hand to hand
combat. Sometimes sparking objects are nearby. Knock them into
it and will die.
On the level where the Agents chase you up the stairs and onto
the rooftops, you can kill them. Before entering the levels, make
sure you have enabled the "Unlimited ammunition", "Unlimited
health", and "All weapons" codes.. At the beginning
of the level, cycle through your weapons and select the grenade
launcher. As soon as an Agent runs after you, shoot him three
times with the grenade launcher. Wait until the smoke clears and
they will be dead.
This trick works best if you are Ghost. In any level that has
an Agent and you are or can get to a roof, go up to the Agent.
He may kick or punch you back; watch the ledges. Hit him once
or twice so that the camera pans to the side. Walk up to him,
punch him, then do a Focus Kick (without pressing a direction).
The agent will fly back. While he is on the ground press [Punch],
[Punch], [Focus] + [Back] + [Punch].
This will do an uppercut, sending him flying. Once he is in the
air, press [Kick] and Ghost will do a flying kick, sending
the Agent soaring across the room. If you are on a roof, do this
to send him flying over the edge, where he dies on impact.
Enable the "Unlimited ammunition" code and obtain the
GP gun (which takes the oxygen out the air). It can kill an Agent.
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