|This mysterious gunslinger comes from the realm of the Mine Flayer.
In order to combat Killithid illusions, his kind learned to use one hundred percent of their arms, as opposed to the more common seventy-five percent.
- Gungamesh teleports around the elevator and attacks once before teleporting again.
- Fires two waves of bouncing bullets in the player's direction.
- Fires four waves of three bullets at the player.
- Starts roaring and summons a line of big bullets at the bottom of the screen. The bullets will move up and down creating a wave pattern, while a circle of bullets increases in size after appearing at the bottom of the screen.
- Falls from the top of the screen to the position of the player and land on the upper part of the elevator, creating a cross of explosions and some small bullets falling down.
- The name 'Gungamesh' is likely in reference to the ancient Uruk king and major figure in Mesopotamian mythology, Gilgamesh but his appearance as a red-robed humanoid with blue skin is a reference to the Final Fantasy series, where Gilgamesh is a multi-armed weapon master from another dimension.
- According to his Diginomicon entry, Gungamesh came from the same dimension as the Mine flayer and seems to be in conflict with the Killithid race. However, since the Killithid's Ammonomicon entry states that "The Killithid exists in a dimension of psychic gunplay, where the need for a gun is superfluous.", it is implied that both Gungamesh's four grey revolvers and his powers of bullet summoning and teleports come from his psychic abilities.
- The line in Gungamesh's description about his kind using "hundred percent of their arms, as opposed to the more common seventy-five percent." is in reference to the popular myth that human beings only use ten percent of their brains.