Nuclear arms were forbidden by the Third Interstellar Armistice, but as large sections of the Gungeon existed before that accord was signed, it is a bit of a grey area legally.
Meltdown - If the player also has Gamma Ray, Gamma Ray branches twice to form a spread of 5 beams, and using Big Boy refills 100 ammo on the Gamma Ray. Ammo restoration only works if Gamma Ray is held when activating Big Boy.
Natural Selection - If the player also has Evolver, it evolves after every 3 unique enemy types killed instead of 5.
Normally invulnerable enemies like Gunreapers can be transformed into Mutant Bullet Kin.
The damage done upon use will contribute to its recharge, even without Ice Cube.
Trivia
This item’s secondary effect that transforms all Bullet Kin into Mutated Bullet Kin may be a reference to the mutating and gene altering effects found in animal species found near nuclear disasters such as Chernobyl.
It could also be a reference to the Ghoul enemies from Fallout, which are humans that have been mutated and turned feral by nuclear radiation.
This item's quote is a reference to I Don't Want To Set The World On Fire by The Ink Spots, a song famously used in Fallout.
The name Big Boy is a reversal of "Little Boy", the code-name for the nuclear bomb which was dropped on the city of Hiroshima in 1945.
The icon of this item likely refers to the Moscow-Washington hotline, commonly referred to as the "Red Telephone" (despite it not being an actual telephone, but rather a text-based system).
Big Boy was reduced in quality from to in .
The explosion created by Big Boy looks identical to that which appears when defeating the Lich.
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Meltdown - If the player also has Gamma Ray, Gamma Ray branches twice to form a spread of 5 beams, and using Big Boy refills 100 ammo on the Gamma Ray. Ammo restoration only works if Gamma Ray is held when activating Big Boy.
