Accidental Aesop: Sometimes characters who are admirable and "cool" in fiction would be the exact opposite in real life. Both the Masked Mutant and Galloping Gazelle are pathetic, petty losers in different ways, and Skipper quickly stops admiring them once he's come to know who they really are.
Broken Base: Depending on who you ask, Attack of the Mutant is either one of the series stand outs for its unique premise and memorable villain, or one of the weaker entries for Stine's lack of comics knowledge and a weak narrative.
Cult Classic: Attack of the Mutant has seen its popularity grow into the 21st century perhaps in part to comic books' increased dominance in mainstream pop culture, and mainly for being viewed as the original series most successful attempt at a black-comic genre deconstruction.
Attack of the Mutant is one long Take That! at comic books, depicting Skipper as having an unhealthy obsession, and most of the other characters finding them pointless. Years later, not only would R.L. Stine write a Man-Thing series for Marvel, but Goosebumps itself would get a comic book series.
Moral Event Horizon: The Mutant killing Molecule Man, who worked for him, For the Evulz. Skipper lampshades it, asking why he would murder a loyal henchman. In the TV adaptation, it's tormenting Skipper just 'cause it's fun before planning to kill him.
To a lesser extent, Skipper tricking the Mutant into melting himself shortly after.
They Wasted a Perfectly Good Character The Masked Mutant actually manages to be a competent, threatening and mysterious antagonist. He's killed off in his only appearance — and in one of the most ridiculous ways possible. To add insult to injury, since the series was revived with the Horrorland books, there've been three separate books featuring comic book villains coming to life, and none of them features the Masked Mutant. They didn't even reprint Attack of the Mutant to go alongside Dr. Maniac Vs. Robby Schwartz even though it was a thematic fit.
The game provides examples of:
Big-Lipped Alligator Moment: The section with the Toadies and the Wicked Wartlock. The characters are not given any kind of foreshadowing, and the only effect they have on the plot is giving the player a telescope for the final battle.
Complete Monster: The Masked Mutant is a comic book supervillain who wants to conquer both his own world and the Earth. To accomplish this, the Mutant has a Slave Race called the Toadies construct the Green Beam, a device that will merge the comic book world and the Earth by converting the latter to 2-D. The Mutant allows the cruel taskmaster the Wicked Wartlock to brutalize and kill the Toadies as he sees fit, and once they finish the Green Beam, the Mutant abducts young children to use as test subjects, turning several into lifeless cutouts that are frozen mid-scream and callously dumped in a storage room in Mutant Headquarters. When the protagonist and the League of Good Guys invade his HQ, the Mutant deploys his henchmen to kill them as he kickstarts "Operation: Total Conversion" by unleashing the Green Beam on major population centers like Washington, D.C. Growing annoyed by one of his untrustworthy lackeys, the Magnificent Molecule Man, the Mutant splits him into his component parts and leaves him to freeze in a Slippy-Slidey Ice World. In the game's bad ending, the Mutant wipes out the League of Good Guys and reduces the Earth to a wasteland, having trapped everyone and everything on it in the comic book world, which he rules over like a God.
