The main gimmick of the game is the spring-loaded boxing glove gun that Willy uses as a weapon. On top of just punching enemies with it, he can also grab and swing from parts of the stage, grab certain projectiles and send them back to the enemy, and launch himself off of the floor and certain objects. The game also included Mega Man (Classic)-style non-linear stage progression (done through choosing "channels" on a TV, a shopping channel for buying powerups, and a "bonus channel" for various minigames to earn cash and extra lives.
Rockin' Kats provides examples of:
- Advancing Wall of Doom: Two vertical sections of the final level have a ghostly disembodied doberman head slowly chasing you through them.
- Airborne Aircraft Carrier: The third part of Stage 2: Sky Ace takes place inside Mugsy's giant blimp.
- Amusement Park of Doom: Level 3 takes place in an Amusement park, with plate spinners, a spookhouse, and a roller coaster. Willy battles the Clown Dog in the boss battle.
- Anachronism Stew: Mugsy and his gang look like 30's gangsters, but the stage select has the player choosing stages on a TV, one of the bosses is a rock band, and at one point Willy rides on a skateboard.
- Beware of Vicious Dog: Most of Willy's enemies are Mugsy's gangster dog minions.
- Blackout Basement: Part of level 5
- Boss Bonanza: The final level (Stage 5) takes you through a series of rematches with all of the minibosses and main bosses you previously faced in the game.
- Brutal Bonus Level: Mugsy challenges Willy to one more fight after the credits, with an ultra-hard level preceding it (and no power-ups.)
- Bully Bulldog: The Big Bad Mugsy is a gangster mob boss bulldog who leads a gang of dogs.
- Cats Are Mean: Inverted. The protagonist is a cat and the main villain (and many of the bosses) are dogs of some kind.
- Creepy Cemetery: Part of stage 3 (though seeing as it's sandwiched between two amusement park sections, it's probably a haunted house.)
- Damsel in Distress: Jill gets herself kidnapped in every level.
- Epic Flail: The Hammer Punch powerup turns the boxing glove gun into this, doing more damage while not being able to grab things.
- Finger Firearms: The level 2 boss attacks with multiple White Gloves, capable of firing bullets by making the Finger Gun gesture.
- Good Animals, Evil Animals: The Cats are the good guys, and the dogs are the bad guys.
- Guns Akimbo: Mugsy during the Final Boss fight.
- Injun Country: The second part of level 4.
- Instrument of Murder: The first stage boss has Willy fighting a rock band called the "Bull Band", with the lead singer attacking you with musical notes.
- Killer Gorilla: Mugsy's personal bodyguard Mr. Kong. Who is fought in the fifth level.
- Levels Take Flight: In Stage 2: Sky Ace, Willy stands atop the wing of a bi-plane being driven by his friend, fighting off airborne enemies. They soon make their way to a large blimp, where a flying dog serves as the mini-boss.
- Marathon Level: Level 5 is basically a Boss Rush with some pretty long stretches of level in-between each boss.
- Levels 3 and 4 aren't as insanely long, but still a lot longer than the first two stages (fortunately, there's mid-level checkpoints that are retained even after continuing.)
- Mascot with Attitude: Strangely enough, the game came out a few months before Sonic the Hedgehog.
- Megaton Punch: The final boss fight ends with Willy punching Mugsy so hard that he goes flying to the moon.
- Minecart Madness: The final part of level 4
- Monster Clown: Clown Dog is the main boss of Stage 3.
- Ninja Pirate Zombie Robot: Gangster dogs, ghost dogs, clown dogs, cowboy dogs, cowboy birds...
- No "Arc" in "Archery": Averted. Archers in level 4 will fire their arrows upwards in an arc. The arrows don't change direction at all, though, making it look very odd.
- Noob Bridge: The player won't get very far without knowing about the floor rebound, swing and Wall Jump techniques (in fact, the player can't even beat the first level without knowing how to use them).
- Outside Ride: Part of level 2 has Willy riding on top of a biplane to fight enemies.
- Polka-Dot Paint: A paint is used which makes white-red striped paint for every odd swipe and blue-yellow polka dot paint for every even swipe.
- Saying Sound Effects Out Loud: "CLOWN-DOG SHOW TIME CLAP! CLAP!"
- Shout-Out: One of the enemies in level 5 dresses like Smooth Criminal Michael Jackson and attacks by moonwalking into you.
- The bat enemies are dressed like a certain Caped Crusader.
- The second-to-last boss is a giant gorilla named Mr. Kong.
- So Once Again, the Day Is Saved: Due to the Saturday Morning episodic nature of the levels, every episode ends with Willy rescuing Jill from the predicament of the episode, with Mugsy ticked off and swearing revenge.
- Super Drowning Skills: Falling in water is instant death.
- Traintop Battle: Part of the first stage.
- Wall Jump: Willy can effectively do this by punching the wall at a downward angle.
- We Will Meet Again: Mugsy says this at the end of every level.Mugsy: "Hey punk! I'll get you yet!"
- When All You Have Is a Hammer…: You can get pretty inventive with the boxing glove gun (and in fact you're expected to.)
- The Wild West: Level 4.
- A Winner Is You: Beating the Brutal Bonus Level gets you the exact same ending as beating the game normally.
- Xtreme Kool Letterz: Rockin' Kats.
