Experimental Mech-Sentinels are robotic guards with cannons as arms. They are stronger and more dangerous than human guards. When defeated, they explode.
Design
The Experimental Mech-Sentinel's original appearance slightly resembled that of a Terminator endoskeleton. The endoskeleton-like design ultimately did not get used in the final game, although its sprites are still viewable with the game's built-in Debug Mode.
Early Mech-Sentinel design