Its animated opening shows pumpkin-headed Dennis deliver the infant Devil in a cage to his master, the resident Mad Scientist Dr. Knarf. The latter is initially annoyed as he was just about to dissect a helpless anthropomorphic eggplant, but soon decides that cutting a cute Devil into "teeny weeny little pieces" is even better! Luckily, our Devil manages to both escape his clutches and wreck the lab with a poorly stored bottle of nitroglycerin, the resultant explosion knocking the Devil all the way into Jersey.
Many years have passed, and Dr. Knarf finally recovered from the damage inflicted on his lab, and was able to finish his experiment to create an army of mutant plants to kidnap Jersey's residents. However, the Devil has now grown up into a defender of Jersey, and is there to rescue the citizens and thwart Knarf's plans.
This game contains the following tropes:
- Adaptational Heroism: Instead of being the evil creature it is in folklore, this version of the Jersey Devil is a hero.
- Airborne Mook: You'll regularly encounter flying insect enemies, complete with a very annoying mosquito-like whine.
- Ambiguous Time Period: While the bulk of the game is ostensibly set in modern times (i.e. the late '90s), the Distant Prologue is a little bit unclear; Jersey Town's growth from a small town with a population of less than 1,000 to the bustling Jersey City in the transition to the present day implies a Time Skip of at least several decades (and that's assuming it had a ridiculously quick urban growth), yet Knarf, who was already middle-aged-looking prior to the skip, doesn't appear to have aged all that much the next time you encounter him.
- Art Shift: The intro sequence is hand-drawn animation, while the in-game cutscenes are presented using the game engine.
- Cerebus Syndrome: Inverted; the game's opening, which shows the resident Big Bad about to dissect cute defenseless critters for fun, is a lot darker than that of a typical mascot platformer, and also the darkest the game ever gets. For the rest of the runtime, Dr. Knarf contents himself with merely kidnapping Jersey's citizens and calls it a needed break from the boring routine of their lives. In the end, he is sent to jail after being defeated and everyone is happy.
- Dark Is Not Evil: The Jersey Devil has black and red eyes, is a devil, and has purple bat wings, but is a good guy.
- Defeat Equals Explosion: All of the enemies defeated by the devil instantly disappear in a puff of smoke.
- Dies Wide Open: JD keeps his default expression upon losing a life in the European version, producing predictable results.
- Down the Drain: The level "Sewer Port" contains a section in the sewers themselves.
- Evil Laugh: The villain, Dr. Knarf, is quite fond of ending his gloating speeches with one. He also regularly laughs during his battle.
- Flash of Pain: The Devil flickers for several seconds whenever he gets hit.
- Flat Scare: The now-grown-up JD does this to Dennis in the intro cinematic—it's worth pointing out that this is the only sound he's heard making in the entire game as he's completely mute otherwise.
- Gonk: The Devil Lady, who Knarf tries to offer to JD as a gesture of "friendship". JD's initial reaction to her is almost as worthy of the Tex Avery cartoons it tries to emulate, but then she shows her true form as a ridiculously huge, fat lady who thuds every time she takes a step and jiggles all over the place in an unflattering manner. You can hardly blame the guy for being a bit put off by her as she tries to kill him like that.
- Good Is Boring: The motivation of Dr. Knarf, as stated in his ending monologue:''Well, well, well. Seems like this beautiful little city has fallen back into its usual peaceful, boring, casual life. Enjoy it, stupid little citizens, because I'll be back!" (crawls out unharmed from a lava pit he fell into after getting defeated by the Devil, only to get arrested immediately after.)
- Heroic Mime: The Devil never speaks; pretty much all the voice acting in the game comes from Dr. Knarf.
- Losing Horns: Heard every time you lose a life.
- Mad Bomber: The pumpkin-headed enemies attack by spamming multiple cartoon bombs at regular intervals. Luckily, both their throw range and the explosion range is so pitifully short that they are easy to deal with regardless.
- Molotov Cocktail: Dr. Knarf throws these from atop a floating platform during his boss fight. You need to deflect them back at him.
- Not Quite Flight: The Devil has a pair of wings on his back, but they are only large enough to allow him to glide down.
- 100% Completion: Fully completing the game requires two things: blowing up each boss's lab and rescuing all the hostages in each location.
- Blowing up the boss lab requires JD to have found and and broken all of the green K Nitro boxes found along the way. Each level has a set amount, both within its hub stage and within the various areas of a level itself. Finding all of them can be a difficult task as you're never told how many are in the current area, only the total amount of the stage in particular, so you'll have to check in more discreet, out of the way locations like corners and the like to be sure you don't miss one.
- Rescuing all hostages, of which there's two in each individual stage, is sometimes trickier as often enough, they too are hidden in out of the way locations. Even if they're easy to spot, sometimes getting to the crank that releases them is the challenge, as some can require you leave some boxes alone so you can use them as platforms to reach high enough. In addition to the 22 found in the 11 main stages, there's also 5 secret levels that can only be accessed once JD's Nitro Power has been raised enough to open them by blowing up each boss lab. Each secret level has yet another 2 hostages for a total of 32.
- Upon completing each level, a K Coin will hover over each stage's sign to let the player know what they're looking for if they're attempting a full completion. Red Coins indicate a level that wasn't completed fully, only beaten; Green Coins indicate the lab was blown up but the hostages weren't saved; Aqua Coins indicate the hostages were saved but the lab wasn't blown up; and Gold Coins indicate the level was fully completed. However, the player will have to keep up with which secret levels they found and completed as those aren't marked at all in the city hub.
- Purple Is Powerful: The Devil is all purple.
- Smashing Hallway Traps of Doom: A very literal example of a hallway with multiple ascending and descending doors that all have spiked edges.
- Spin Attack: The titular Devil can spin around to smack the enemies with his tail.
- The Many Deaths of You: Rather surprisingly for a game like this, there's quite a few death animations for JD when he loses a life
- The standard for running out of HP due to hits has JD wobble in place before falling forward unconscious.
- Falling down pits shows a stone floor as in the "lost HP" scene that shows his shadow growing as he falls further and further before he lands in a heap on the ground
- Falling into water shows JD sinking quickly down and slowly coming to rest on the bottom of the water bed. The appearance of the scene depends on if he fell into the regular ponds found throughout the stages, the toxic sludge of the Toxic Factory, or if he fell into the murky waters of the Sewer
- If JD happens to fall into the flaming ground of the Toxic Factory's hub level, the same animation for having lost HP plays, but while he's standing in a field of flame....probably the darkest and creepiest scene since it calls to mind JD standing in Hell.
- Strangely enough, JD does take fall damage, which decreases his HP AS he falls instead of when he lands if he falls a long ways. If he happens to run out of HP while falling but before he lands on ground or before he falls far enough to hit the threshold for falling down a pit, the "Lost HP" scene plays as if he got hit by an enemy or trap.
- We Can Rule Together: Knarf attempts to pull this on JD in the attic of the Haunted Mansion if you happen to return to the Cemetery level to explore that stage, offering him the companionship of the Devil Lady to try and persuade him to become friends with the doctor.
- Where It All Began: A slight variant of the trope as the player themselves didn't openly play the game starting at Knarf's house laboratory, but the final level involves Jersey Devil climbing his way up the forest hillside to confront Dr. Knarf in his house, where his emnity with the mad doctor started when he was an infant.
- A Winner Is You: The European version of the game simply cuts straight to the credits after JD flies away from Knarf's now-destroyed laboratory.