The objective of the game is for the player to shoot down robots and take control of them. Once the player has taken control of the robot, he/she has the robot's weapons and upgrades. The player can take control of many different types of robots. The player must rescue all the civilians in order to proceed to the next stage. The game has a two player cooperative mode.
Throughout the game, the player moves his way shooting a robots, aliens, mutants and huge vehicles that tries to impede the player's progress. There is a total of 9 robots the player can take control of, each with different abilities and weapons.
Power-ups are provided at various levels. List of power-ups includes:
- Health - Restores the player's health to 100%.
- Power Upgrade level 1 - The player's bullets turns green, and is more lethal than the player's default weapon.
- Power Upgrade level 2 - The player's bullets turns blue, and is even more lethal than green,and to some extent capable of performing special functions (like homing into enemies, firing at two angles spread 90 degrees apart, etc.).
- Proximity Mines - The player will drop it on the floor, then lure enemies to walk over it. After 5 seconds, it will explode, causing massive damage(even to the player him/herself who got too near).
- Explosion - Once used, an explosion will appear directly in front of the player. The player will not be harmed, but enemies ahead would.
- Homing spike - A spiked ball that floats in the air, circling the player, stabbing enemies around the player and causing major damage. Even large mutants will die in one hit by this weapon.
- Floating robot aide - A round, mechanical ball that floats around the player, similar to the homing spike. When the player shoots at enemies, the robot aide will fire bullets (similar to the player's default pistol's) at nearby opponent. It can cause minor damage to enemies, though not as deadly as the homing spike. It only appears at the few final levels.
No shooter game will be complete without a plethora of deadly enemies. Here are just a few basic opponents which players will encounter at each level.
- Alien soldiers - the most common type of enemies, the aliens responsible for conquering earth usually comes in large numbers, firing at players with firearms. In the first few levels they appeared with pistols (similar to the player's default weapon) but later on they will utilize rifles and connons. In the "Hospital" level, some aliens will even attack with large claw-like appendages that have replaced their arms. The aliens' appearance appears to be the stereotype of grays according to human's perception.
- Grubs - Large, insectoid enemies that spits acid at the players. In the first few level they appear, the giant grubs are purple in colour, but later on they appear red. Being huge opponents (a grub is five times the size of an alien) they are easy targets, but requires a lot of shots to kill, and their acidic spit can cause great damage to the player's health. A good strategy against this type of enemy is to attack from up close, where its acidic spit will mostly miss its targets.
- Robots-the robotic technology that was manipulated by the aliens. Players, after defeating a robot, can possess and control it.
- Turrets - turrets that are built by the aliens. These turrets are huge, and moves around on an axis built at its base. When attacking, they fire large cannon shells and can cause massive damage. They can still be defeated because they are immobile.
-Mutants - humans that are turned into mutants by the aliens. Comes in different shapes and sizes, but most of then looks horrific and disgusting. For instance, in the Hospital level the mutants only has the upper half of their body remaining, whilst in subsequent levels the mutants are black or green. Attacks from close range, and could be easily killed with one default pistol's shot.
- Flying aliens - aliens that looks like dragonflies, flying in circles and dropping bombs on the players. Only appears in outdoor levels(such as Rooftops, Alien City).Has a low endurance and could be shot if up close.