Earth Defense Force: Insect Armageddon is a straight combat shooting game where aliens invade Earth and intend on destroying human life with the aid of bio-engineered insects. The player takes the role of Lightning Alpha, the leader of an elite defense of fighters called Strike Force Lightning. The story has three independent chapters with five separate missions. The first chapter is the game intro and the second is the reconnaissance of the team as they move across the ravaged city. The third chapter is the transport of “The Cube” to destroy the insects’ lair (nest). The insect Queen engages the defenders before “The Cube” could be dropped.
Earth Defense Force: Insect Armageddon can support two-player split screen, three-player online coop, and a maximum of six players in Survival mode. Earned credits are accumulated and may be used on a wide variety of tasks. There are over 300 weapons available for purchase including a new unlock system. Some weapons are dropped by elite enemies. There are four classes of armor on the menu and players can customize armors (trooper armor, jet armor, tactical and battle armor). Trooper armor is standard and with upgradeable abilities, available only in Survival mode. Jet armors are for sky fights (the fastest but weakest), tactical armors are for support, and battle armors are the most damaging to enemies.