In Galaxy Defenders: Extinction Protocol, the agents cross a portal to the invaders' home planet, to fight the final battle against the Aliens. The adventure begins after the Agents defeat the Aliens on the Moon in Operation Strikeback.

Extinction Protocol adds many new features and new mechanics, introducing new aliens and new characters. Master Aliens, the highest-ranked invaders in the Alien Army are present in this set, including the Kingator - a giant creature, half reptile and half war-drone - and the Alien Queen, a nearly invincible opponent that can poison her victims before she finishes them with her dreadful claws. The Agents can face these new enemies wearing lethal Power Armor, the ultimate mobile exoskeletons capable of imbuing the Agents with new unique powers and awesome firepower!

Agents are no longer alone in this war, as Extinction Protocol introduces a Non-Player Character (NPC) system, allowing intelligent non-player agents to fight side by side with the GD squad.

The underground of the alien planet is formed by endless narrow corridors and caves, represented by a new system of Modular Map Tiles, fully compatible with all previous maps of the game. The Extinction Protocol box includes new miniatures, new cards, new maps, a storybook and a new rulebook.

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