In the early 21st century, the Earth is under attack by aliens. In five areas of the planet, they have erected energy generators, creating a field that slowly encompasses the entire planet surface. They have also taken hundreds of humans prisoner. Someone has to stop them. Enter Russian Commander Ivan Popovich, nicknamed "Krazy Ivan". He is a paranoid schizophrenic, prone to burst out into violence at any time. In other words, he's perfect for the job.
The player controls Ivan's "Steel Cossack" power suit on the three-dimensional battlefields. In each of the five areas in the game, two kinds of enemies can be found: Drones and Sentients. Drones are smaller air and ground vehicles that often respawn. Sentients are mechs similar in size and capability to the Steel Cossack. Each of the Sentients must be eliminated before the energy field generator can be destroyed to complete the mission.
The Cossack is capable of carrying lots of weapons: projectile and energy guns, unguided and guided missiles, and other special weapons. Destroyed enemies reveal captured humans, to be rescued by Ivan, and power-ups, which recharge shields or rearm weapons.
After a successful mission, Ivan can upgrade the Cossack with more powerful weapons and replace the mech's armor.
Between the missions, rather humorous live-action cutscenes (starring English actors sporting thick Russian accents) continue the story.