The Walker is a two-legged mech that is approximately twice the height of an average Marine. It has two weapons: a six-round self-reloading launcher that fires homing/free-fly missiles, with a linked cannon and machine gun in a gun pod on the right shoulder. For defense purposes, the Walker is equipped with both regenerative armor plating and energy shields.
When compared to other SMC ground vehicles such as the Hovertank, the Mech is quite slow as it doesn't rely on anti-gravity technology, but is instead propelled by its reverse-jointed legs.
It seems that Walkers are normally utilized for anti-infantry or infantry support purposes rather than fighting against heavier Strogg vehicles. However, according to a demoralized marine in the level Perimeter Defense Station, they are not able to deal with extremely large numbers of infantry, which is revealed to be at least partially true in the game. Due to the inferior energy shield protection and low mobility they are considerably easier to destroy than the SMC Hovertank.
The Walker is normally only accessible to the player in the level Construction Zone. When fighting smaller enemies like Guards, Gunners and Turrets, the machine gun is more than sufficient. Should the Walker's armor levels become dangerously low, a volley of rockets quickly eliminates all foes, giving "breathing room" for the regenerative systems to perform repairs. The Heavy Hover Tanks encountered in the course of the level are too fast for rockets, so reliance on the heavy machine gun at mid-ranges is highly recommended against these foes. Also the machine gun is useful for shooting down these guided missiles fired by hover tanks. If the quick response at close range is needed, fire all 6 rockets for maximum effect, as 6 rockets can kill almost anything you encountered, as long as these rockets find their mark. The rockets will be loaded individually, it will take about 5 seconds to load 6 rockets, use caution when fighting a lot of enemies, you can use machine gun while loading the rockets. The Walker has a poor mobility, so you have to be aggressive when dealing with agile foes like Hornets. If you are too hurt to continue, as your shield is depleted, pull back while you still can.
The only occasion on which rockets are required is during the battle with the Harvester at the end of the level. Here, fire one or two salvos of rockets, quickly switch to the machine gun to eliminate its homing missiles, before finally switching back to rockets again. Frequently make use of cover and hit-and-run attacks to prevent the Harvester from closing range and unleashing a barrage of blaster shots which can make quick work of the Walker's armor and shields. When dealing with this enemy, the rockets can be lock-on and behaves like a guided missile.