From Sonic Retro
I have relatively little idea of how the gameplay in GUN Fortress is like. Can anybody help out here? -Uncle Otis, 7:14 CT, May 1st 2010.
Gameplay in G.U.N. Fortress has some similarities to that of Air Fleet, the other level in Shadow to be set in a United Federation military facility. Extremly long, curving corridors are to be found throughout, interspersed with occasional larger, circular rooms, and large underground caverns (bordered by bottomless pits) where the Mother Computers can be found. The main distinguishing feature of the Fortress, however, is its waves and waves of GUN mechas. While footsoldiers are present in the vehicle depot at the very start of the level, bipedal mechs soon take over the defense of this last human stronghold.
Fighting in this level takes Shadow gradually downwards, as he delves further and further towards the core of the base. Underground roads bored through the bedrock make up most of the passageways, although quick sprinting through is impeded because the defenders keep closing blast doors right in front of you, which have to be shot or spin attacked to pieces - a similar situation occurs in the Soleannan stronghold of Aquatic Base in Sonic '06. GUN robots also tend to teleport in on Shadow while the doors hold him up - functioning more as an ammo supply than a threat, in reality. Some of the larger rooms require you to destroy all enemies in the vicinity in order to unlock grabrail machines that take Shadow to an upper exit; use of fixed turrets to take out high-up enemies is necessary.
A curious and unique feature if taking the Doom's Eye's Dark route comes when approaching th Mother Computer caverns. The view switches from a third-person perspective behind Shadow, to the security camera feed of the coridoor in question. Accustomising to the sudden change in control style can make the sections far more difficult than one would expect, as Shadow is supposed to move swiftly between patches of cover to prevent the camera's auto-cannon from opening fire.
When normal perspective returns in the Mother Computer chambers, Shadow has to carefully jump between strobing laser doorways above bottomless chasms. Climbing on turrets is again necessary to destroy the huge blue mainframes, as they're positioned out of range above freight lifts that disgorge an infinite supply of combat mechas.
In Shadow the Hedgehog, this stage is only ever referred to as "GUN Fortress", yet on this wiki it is named "G.U.N. Fortress". While the latter name makes more sense (considering that this is a fortress of G.U.N. - a military organization), it may be more logical to be more consistent with the game itself. Basically, the question is - should we rename it to "GUN Fortress" here, for the sake of uniformity with the game, or should we not bother?