GUN Soldiers are human combatants that wear ballistic combat helmets with solid white visors concealing their identities. The standard GUN troop wears a blue or black uniform with a ballistic vest, while others wear camouflage gear, such as desert or jungle colors, to match the environment in which they are deployed.
Unlike other enemies in other games in the Sonic the Hedgehog series, GUN soldiers talk and communicate with one another, in addition to yelling battle cries in combat. As G.U.N. is the Sonic the Hedgehog equivalent of the real-life U.S. Army, they act similarly to real soldiers; giving orders to attack, devising tactics, providing status reports and requesting assistance, in example.
While GUN Soldiers are dedicated and loyal, they are also stubborn. When issued to attack Shadow the Hedgehog, they show no hesitation in going head-on against him. When Shadow defeats the troops, leaving them wounded on the ground, they will show mercy and beg Shadow to spare their lives, showing that they may only fear dying.
GUN Soldiers are shown to take orders rarely without question. G.U.N.'s raid on the Space Colony ARK fifty years prior to the events of Shadow the Hedgehog showed that the troopers in that time period had a merciless attitude towards their mission, unafraid to terminate nearly all the Ark's inhabitants.
Sonic Adventure 2
In Sonic Adventure 2, aside from the typical robot forces tasked with stopping any threat, GUN Soldier make a few appearances in cutscenes. They are also seen controlling robotic forces like the F-6t Big Foot.
Shadow the Hedgehog
In Shadow the Hedgehog, they are the primary enemies/allies in the game, at war with the Black Arms. After the mission in Westopolis, they begin to attack Shadow on behalf of the Commander's orders. GUN Soldier have a diverse arsenal of weaponry at their disposal, ranging from firearms such as handguns, automatic weapons and Bazookas or knives for close-range attacks. They are one of the weakest enemy types in the game and can be defeated with one hit using most attacks.
GUN Soldiers do not technically die when they are defeated, but are instead knocked to the ground, severely wounded. In this state, they will groan and beg Shadow the Hedgehog to spare their lives, even though Shadow does not have the option to finish them off. However, if the player heals them with the Heal Cannon or Heal Units, they will salute and compliment Shadow, and no longer fight, until the player attacks them, upon where they will start attacking him again.
Sonic the Hedgehog (2006)
In Sonic the Hedgehog (2006), a total of four GUN Soldier make appearances during gameplay, but only in Shadow's story. They each provide Shadow, who is an agent of G.U.N. in this game, with one of his Town Missions. Two of them have known names (Herman and Parr), while the other two are unnamed.
GUN Soldiers will stop firing if the player use the Heal Cannon and will salute Shadow.
As it may have been considered inappropriate for a Sonic game, GUN Soldiers are never shown dying.
The only time any soldiers are shown to presumably die is during the opening cinematic for Shadow the Hedgehog, where most are caught in explosions or shot, as well as in the scene when Shadow angrily stands on top of a lone soldier.
Although soldiers are seen piloting the F-6 series in Shadow the Hedgehog, when the mechs explode, there is nothing left of the pilots.
Due to the clumsy enemy AI in Shadow the Hedgehog, GUN Soldiers and Black Arms cannot engage in combat properly. Even when there are no remaining alien targets, GUN Soldiers will continue to fire their weapons, shout combat dialogue and strafe around as if they were still battling.