The Ghen are aliens who recently entered our solar system in an apparent attempt to establish diplomatic relations with humans and forge a new era of peace within the galaxy. That was their cover, at least. Now they've shown their true colors and revealed themselves as the violent world-conquerors that they are. The leaders of Earth are all under their control, and no one can stop them from reigning supreme. No one but you, of course. As a deep space engineer, you and your powerful exo-suit are the last hope for humanity. It is up to you to defeat the onslaught of enemy hordes and save the world...perhaps even the galaxy.
Unlike many first-person games, which feature humans on foot as protagonists, Ghen War blends itself with the mech genre, putting players in an exo-suit that has a variety of different powers. From extra strength that allows you to take a high amount of damage to a number of different weapons to deploy, the exo-suit will aid you in your assault against the Ghen. Unlike a foot soldier, however, the exo-suit has some unique movements that must be mastered. Players can look all around while inside the suit, but the default setting has the mech looking straight ahead, even when climbing uphill. The different weapons that can be acquired include missiles, mines, grenades, lasers, and even a decoy that you can drop to confuse the Ghen.
Your enemies are certainly not without their own powers. There are a variety of Ghen for you to do battle with, ranging from the usual grunts to larger enemies such as Dragon transports, Behemoths, and Snails. All of the enemies are part biological and part machine, and while they retain some characteristics from the creatures they emulate, none of them are short on firepower.
The game sports six different fighting areas, including Venus, Mars, Deimos (a Martian moon), our own moon, Australia, and NORAD, an actual air-defense base in Colorado. Most of these areas are broken up into four or five different missions, which include objectives such as blowing up reactors or rescuing prisoners from their Ghen-built prisons.