Join the resistance, join the Fifth Column! Expand the Galaxy Defenders Agency's army with these new powerful agents and unleash their unique new classes, powers, and items against the alien invasion! The Fifth Column option adds four new agents to the game:

- one Archon - members of an alien race struggling desperately against the invaders, Archon soldiers can influence the course of the battle using psionic powers and alien weapons

- one Knight - originally 'just' a clone with extraordinary abilities, the Agency has chosen him as a new recruit. The Knight can be played as a Support class agent, equipped with multiple devises and capable of moving quickly where he is most needed. Alternatively, as a Guardian class agent, he acts like a mobile defence unit, capable of intercepting attacks directed at his teammates and ''controlling'' aliens.

- two Bio Power Armor - These incredible weapon platforms are living beings that become symbiotic with their Agent-host, turning him into a veritable war machine, with powerful defence and awesome attacks. Fifth Column may be used to replace the agents in any Galaxy Defenders mission (Core Set, Operation Strikeback, Extinction Protocol) to enhance your game experience.

This is not a complete game. A copy of Galaxy Defenders is required to play.