As a Falling Blocks game, Monster Slider presents the player with a field and blocks in six to eight colors depending on difficulty: orange, red, yellow, green, purple, and blue are the default ones and cyan and white the extra two. Three of any given color need to be touching to be eliminated from the field. The signature gameplay feature that Monster Slider brings in is that the bottom of the field is tilted. The player can change the direction of the tilt as they please and this will cause the blocks to slide towards the new lowest point. Timely tilts can be very useful in creating chain eliminations. Eliminations are good for keeping one's field empty, scoring points, and thwarting the opponent. Every time an elimination occurs, a golden skull is generated. Gold skulls can be spent to summon silver skulls from the opponent's field's ceiling. Silver skulls are blocks that can only be eliminated by touching other blocks that get eliminated. A row of skulls will just keep sitting there. It's game over when the blocks and skulls fill up the field.
New compared to the previous game are candles in the center of the screen. They burn up with time but opponents can get the other's candle to burn up faster with chain eliminations. Even just a 2-pointer will drastically cut into the opponent's candle duration. Some characters also can directly attack the opponent's candle by means of their special ability. If a candle is fully burned up, that means it's game over for its owner regardless of what the fields look like. This being an arcade game, the candle ensures that matches only last as long as is deemed reasonable for the payment.
Story mode offers a selection of three protagonists: Niina, Kiil, and Doefsky. In two-player mode, they and all of the twelve antagonists can be picked from. Each character has a unique special ability that can only be activated by eliminating a star block. Doing so generates a character-specific emblem and much like gold skulls, emblems can be spent as the user deems it strategically sound. One emblem pays for one usage of the character's special ability. As an example, Niina's Holy Sphere plants a holy cross in her opponent's field. A holy cross can never be made to move from where it is planted and like a skull can only be eliminated when color blocks adjacent to it are eliminated. As another example, Kiil is one of the few characters whose special ability directly targets the opponent's candle, which he cuts short with a swing of his sword.
The arcade game is an Alternate Continuity to the original game. Crodia gets abducted by Draqula and his monstrous servants, prompting her younger sister Niina, the guard Kiil, and the priest Doefsky to set out to rescue her. Any of them battles their way from the cemetery to a waterway that leads into a cave system and then up into Draqula's castle. Despite a barrier that has been put up to negate the hero's special ability, Draqula is soundly beaten. Crodia then reveals that she's been the mastermind for a while now, having defeated Draqula herself and taken over his castle. She enjoys her run as monster boss and refuses to leave, so the protagonists have to battle her to get her to come home.
Keeping in mind that reviews of either game are scarce, the arcade version is considered inferior to the Sega Saturn version, accounting for its remarkably short run. The arcade version ditches the spooky visual and audial aesthetic that set its predecessor apart from Puyo Puyo to make it more alike Puyo Puyo. On top of that, while the game shows signs of wanting to be a step up from the Sega Saturn version, such as by providing each character with a personalized field design, compelling content like Pre-Battle Banter and story have been cut back on. The presence of character audio files that never activate during gameplay suggest that the game was rushed, possibly to keep the release date in the wake of Puyo Puyo Sun.
Monster Slider contains examples of:
- '90s Hair: Uga has a flattop that's about as tall as his body is. His bolts are screwed in on top.
- Abhorrent Admirer: Cyasarin is immediately smitten with the handsome Kiil. Kiil is not interested in the avances of an okama skeleton and is characteristically but still excessively rude about it.
- The Alcoholic: Gon Zo carries around a bottle of alcohol wherever he goes and he has a jovial and slurred way of speaking that suggests repeat-drunkenness.
- Ash Face: Uga is left momentarily all blackened when he executes his special ability, as he's effectively a living lightning rod with his tall hair and inevitably catches a zap himself from the lightning he summons.
- Attract Mode: One part of the attract mode is a bare-bones depiction of Crodia's abduction that sets up Draqula as the big bad. It also introduces the three protagonists, giving significantly more focus to the cute Niina than the other two. The other part is an explanation by the referee-esque critter how the game is played.
- Bedsheet Ghost: One of Draqula's henchmen is the ghost Naitou, who looks like a white blob with a spear and a helmet. His face appears to be drawn on him and he can switch between three drawing styles: a dot-eyed neutral face, a face with large and detailed eyes, and a face that too is dot-eyed but where the shocked expression gets a lot of detail. Naitou is one of the random opponents and his special ability is to take duration points from his opponent's candle and add it to his own.
- Belly Mouth: Gon Zo's head is entirely wrapped up in bandage. He may or may have a normal face, but either way he has eyes and a mouth on his torso — on top of the bandage there.
- "Blind Idiot" Translation: Several characters have non-Japanese names. In the two-player mode character selection screen, the names are displayed in both katakana and Roman script and very few non-Japanese ones get rendered as what they may be expected to be. Some of these are intentional, but others don't seem to be. Niina should've been Nina, Kiil should've been Kiel, Ririan should've been Lilian, Cyasarin should've been Catharine, Patolisia should've been Patricia, and Crodia should've been Claudia. Naitou and Draqula get addressed in their profiles: Naitou is an intentional and untranslatable pun on "Knight" and the Japanese name "Naitou", while Draqula's profile curiously states that the name is spelled with a "c" and not with a "q".
- Boring Religious Service: In Doefsky's ending, he insists that Crodia sits down for a prayer of gratitude for their safety for 3 hours and 45 minutes. She very much doesn't want to and tries to get away.
- Brought Down to Normal: Crodia has set up a barrier in the castle that prevents intruders from using their special abilities. It does not affect her or Dracula, meaning they have a big advantage compared to Niina, Kiil, and Doefsky when any of them comes to save Crodia.
- Calling Your Attacks: Only Niina, Draqula, Ririan, and Gon Zo call out their attack by name, all four of which in English or German.
- Camp Gay: Cyasarin is a self-described okama and seemingly works at an okama bar called Hakachi (The Boneyard). They wear makeup, a wig, and a large bow on their head, and their special ability has them posing in front of a giant heart while sending out projectile kisses. Cyasarin is smitten on sight by the handsome Kiil, but he wants nothing to do with Cyasarin.
- Charged Attack: Both the gold skulls and the emblems can be saved up for bigger attacks. Being able to spend five at once of either makes the attacks especially powerful. Five+ gold skulls can be exchanged for more than one silver skull per gold skull and five+ emblems create more efficient or longer-lasting
- Childish Older Sibling: Crodia is a selfish, irresponsible, and unpredictable woman, while her younger sister Niina is a typical good girl: polite, brave, and looking out for others' wellbeing. Niina becomes quite exasperated with her older sister's antics.
- Child Soldiers: Masaru is a child who looks about ten. He and his mother serve as one amidst Draqula's forces and by the looks of the attract mode he may have also been involved in Crodia's abduction.
- Contrasting Replacement Character:
- The snowman Carrot takes the place of the yeti of the previous game. There is a bit of wordplay involved here because the Japanese word for yeti is "yuki otoko" — "snow man". Furthermore, Carrot is dressed in an outfit resembling an elementary school uniform while the previous game's yeti is the most elderly looking of its cast.
- The werewolf Mikazuki takes the place of the wolfman of the previous game. While the brown-furred wolfman is an arrogant and bare-chested brute with cuffs on his wrists, the grey-furred Mikazuki is polite and clothed in a classy kimono.
- The golem Muscles takes the place of the golem of the previous game. While the other golem is an undressed, lean bodybuilder, Muscles is a sumo wrestler wearing a fancy tsuna.
- Creepy Cemetery: The cemetery is the first area the protagonists need to cross to reach Draqula's castle. They fight two random monsters there and leave the area after defeating Cyasarin.
- Creepy Crossdresser: Cyasarin is a skeleton to begin with. The femininity of their look is accomplished with makeup, a wig, and a bow that all together look both dated and garish. Other than serving Draqula, Cyasarin isn't much of a bad person and quite friendly unless provoked, like when Niina and Kiil insult them for being okama.
- Crucial Cross: Nina wields a holy cross during her efforts to save Crodia from Draqula and the monsters in his employ. It is the source of her special ability Holy Sphere.
- Cute Witch: One of Draqula's henchmen is the witch Ririan, who wears a minidress version of classical witch attire and wields a silly-looking wand. Ririan is one of the random opponents and her special ability, Metamorphose, is to transform herself into a palette swap version of her opponent and give them a taste of their own special ability.
- Damsel out of Distress: Crodia gets abducted by Draqula and his servants. Rather than despair, she views her time as a captive as spare time and not wanting it to go to waste, she defeats Draqula herself, gets him to serve her, takes over his castle, and just for fun sets up a barrier that prevents special abilities from being used. This is primarily a security measure, but also allows her to mess with her would-be saviors. In the end, she has so much fun that her would-be saviors have to fight her to get her to come back home. Even after that, she can't stop being excited about her adventure. In Niina's ending, she recommends her sister to get abducted too some time. In Kiil's ending, she wonders if she can find someone else to abduct her next.
- Dem Bones: One of Draqula's henchmen is the skeleton Cyasarin, an okama who works at or even runs an okama bar called Hakachi (The Boneyard). Cyasarin is the first default opponent encountered, being the last one fought in the cemetery. Their special ability is to blow a kiss to their opponent's field, summoning a minimum of three skulls per kiss to come rain down.
- Dracula: Draqula is a blue-skinned vampire, the owner of a castle, and the wealthy boss of a small legion of monsters. He abducts, for unshared reasons, Crodia, probably not expecting that she would beat him into submission and take over his operation. He seems to be okay working for her because he speaks proudly about the special ability-nullifying barrier Crodia gets set up. Draqula's special ability is Evil Bat. It summons at minimum seven bats to his opponent's field that suck the life force out of the blocks they land on. These blocks become skulls.
- Dramatic Thunder: The cinematic attract mode ends with a closeup shot of Niina's eyes. Thunder resounds during it, signifying the perilous quest up ahead.
- Education Mama: Masaru's mother is identified as a "kyoiku mama" in their profile, which also makes a note that while they as a team carry the boy's name, it is his mother who does all the talking and, presumably, decision-making.
- Facial Markings: The werewolf has a crescent moon on his forehead. This relates to his name, "Mikazuki" ("third day moon"), which is a Japanese term for the crescent moon.
- Fish People: A pair of Draqula's henchmen are the two gillmen Masaru and his mother. The former is a studious tyke, the latter his overbearing education mamma. The two are more fish-like than gillmen usually are, having a penguin-like physique and simple facial features. Masaru and his mother are among the random opponents and their special ability is to transform herself into a palette swap version of her opponent and give them a taste of their own special ability is to temporarily summon a pool of water that raises the floor of their opponent's field.
- For the Evulz: It's never explained why Draqula abducted Crodia. There's no hint of romantic interest and while Crodia's outfit in the attract mode suggests her to be nobility, neither financial nor political extortion are brought up either. So, that leaves Draqula's motivation for the abduction as him doing it because he can.
- Frankenstein's Monster: One of Draqula's henchmen is the Frankenstein's monster Uga, who is a distinctly '90s redesign of the Universal look. Most notably, he sports a flattop about as tall as he his and his bolts are located at the top of it. Uga is one of the random opponents and his special ability is to summon down lightning that temporarily darkens his opponent's field except for the falling block. This makes it hard to color match.
- Golem: One of Draqula's henchmen is the golem Muscles, also known as Muscles Iwa-Otoko (Muscles Rockman), who is a mustache-sporting golem and a tsuna-wearing sumo wrestler. Muscles is the second default opponent encountered, being the last one fought along the waterway. His special ability is to perform shiko and thereby force boulders out of the ground that raise the floor. The only way to remove the boulders is to eliminate blocks adjacent to them.
- Green Thumb: Crodia's special ability is to sprout vines from her opponent's field's floor. These grow over their blocks and covered blocks cannot be part of an elimination row. The only way to remove the vines is to eliminate blocks adjacent to them and even then they'll only retreat as far as the eliminated blocks touched. How Crodia is able to do this is not explained. The special abilities of the other characters come from them being monsters or wielding weapons, while Crodia goes into battle barehanded and she's ostensibly human.
- Lighter and Softer: The arcade game removes pretty much every spooky element of the console game. Niina goes from a Gothic monster hunter to an angelic figure. All monsters have gotten overhauls that make them more quirky and less threatening. The backgrounds are less distinct and therefore provide less atmosphere. And the music goes from haunting and even intimidating to bright and sparkly.
- Losing Your Head: When Carrot performs his special ability, he takes his hat off and his head along with it. Snow spews upwards from his neck until he puts his head and hat back.
- Magic Wand: Ririan wields an odd-looking magic wand. It consists of a swirled yellow stick topped with what looks like a pink tomato with eyes and wings. It grants her the ability to change into her opponent and copy their special ability.
- Medusa: Patolisia is midpoint between snake person and gorgon in that she looks like if someone cut a snake in half and then inserted a human upper body between the two halves. The one snake head on her human human is all she has for hair and it seems that the two heads are of one brain. As a proper gorgon, Patolisia has a petrifying gaze that she can unleash on her opponent's blocks. Petrified blocks act like skulls until adjacent blocks are eliminated. Then they return to normal.
- Miniature Senior Citizens: Counting only from feet to shoulders, the elderly priest Doefsky is about a fourth the height of all other adult characters. With head, it's about a third.
- The Minion Master: Carrot has at minimum three little snowmen that are his companions. One has a red scarf, another a yellow snow cap, and the third a blue snow cap. They freeze Carrot's opponent's blocks for him if he uses his special ability.
- Mood-Swinger: Naitou has what appears to be a drawn-on face that comes in no more than three varieties: neutral, awe, and shock. He cycles between these three as the situation calls for it.
- Mummy: One of Draqula's henchmen is the mummy Gon Zo, who lack a face on his head but has one on his torso. He's also never far away from a bottle of alcohol and by the sound of his voice regularly takes sips. Gon Zo is one of the random opponents and his special ability is Pharaoh Magic. This gives him temporary control over his opponent's falling blocks.
- Noblewoman's Laugh: If she wins, the powerful and ostensibly wealthy Crodia laughs a noblewoman's laugh.
- No Name Given: The gill-family duo consists of a mother and a son and is jointly called Masaru. Masaru is specifically the name of the son, while the mother's name is left unstated.
- Onee-sama: Niina refers to Crodia as "onee-sama" and she herself is the polite young girl archetype. This sets up the expectation that Crodia is even more ladylike. This isn't the case: Crodia is selfish, arrogant, and indifferent. It is quite a shock for Niina after all she did to save her.
- Opaque Nerd Glasses: Masaru, an overachiever spurred on by his tiger mom, wears opaque glasses with thickness swirls on the lenses.
- Our Werewolves Are Different: One of Draqula's henchmen is the werewolf Mikazuki, who has a crescent moon mark on his forehead, dresses in a kimono, and wields a katana. Mikazuki is one of the random opponents and his special ability is a powerful sword slash that cuts down his opponent's candle.
- Palette Swap: Ririan's special ability lets her change into her opponent, but she's always distinct because her palette is different. For instance, as Mikazuki she wears a red kimono instead of a blue one and as Gon Zo her lips are purple instead of red.
- Power Copying: Ririan's magic wand allows her to take the shape of her opponent and use their own special abilities against them.
- Pre-Battle Banter: Only the four default opponents — Cyasarin, Muscles, Draqula, and Crodia — make time for conversation prior to combat. What they say differs little between which protagonist goes up against them.
- Pre-existing Encounters: A play through story mode consists of eight battles. Four of these are against pre-determined opponents. The other four spots are randomly filled by Carrot, Mikazuki, Ririan, Masaru, Gon Zo, Uga, Naitou, and/or Patolisia.
- Projectile Kiss: Cyasarin's special ability has them pose in front of a heart and blow one or more kisses to their opponent's field. This causes at minimum three skulls per kiss to come rain down.
- Robe and Wizard Hat: Ririan wears the classical witch attire, but with the robe redone as a minidress. Further adding to her cute take on the look is that her hat is decked out with stars.
- Schrödinger's Player Character: There are three protagonists to pick from to save Crodia. Niina is her sister and therefore fully personally motivated. Kiil is a guard and acquainted with Crodia. And the priest Doefsky seems to be a religious figurehead of their community and motivated by duty. Whichever one the player picks, the other two won't have a role in the story.
- Secret Underground Passage: There is a route into and from Draqula's castle that goes through a cave system and follows a path outside along an underground river. It is not technically secret because both the protagonists and Draqula's servants know about it and use it, but it is an underground route that is not part of the castle's structure. Nina battles one monster outside the cave, one monster inside the cave, and faces Muscles at the end of it.
- Shock and Awe: Uga summons down lightning as his special ability. It inevitably hits him, what with his tall flattop topped with bolts essentially making him a lightning rod, but he brushes it off readily.
- Shout-Out: When Muscles deals with Kiil, his intro speech includes the sentence "Washi wa ima made no zako to wa chigau de gowasu zo!" ("ワシは今までの雑魚とは違うでゴワスぞ!"). This line is reminiscent of Mobile Suit Gundam Ramba Ral's famous quote "Zaku to wa chigau no da yo!" ("ザクとは違うのだよ!"), also known in English as "This is no Zaku, boy! No Zaku!" Muscles somewhat looks like Ramba Ral too.
- Significant Wardrobe Shift: In the attract mode, Crodia is depicted as wearing a fancy mauve dress and lots of jewelry, suggesting that she's nobility or at least wealthy. When she's encountered as the final boss, she's replaced her jewelry with one necklace and one crown-like hair piece. She's too ditched her dress for a raisin-purple emsemble of a top, a skirt, gloves, and boots that leave her belly, arms, and legs exposed. What has changed is that Crodia beat Draqula herself and took control of him, his servants, and his castle. She's enjoying being a pro-active monster boss.
- Snake People: Although she has the gorgon hair and stare, Patolisia's profile does not identify her as a gorgon, but as a snakewoman (hebi-onna). She has a human upper body, a snake lower body, and a snake's head growing from her human head instead of hair. Patolisia is one of Draqula's henchmen and noted as being the kindest monster of the lot. She is one of the random opponents and her special ability is her gaze that turns some of the opponent's blocks to stone. Petrified blocks act like skulls until adjacent blocks are eliminated. Then they return to normal.
- Snowlem: One of Draqula's henchmen is the living snowman Carrot, whose manner of dress resembles an elementary school uniform and whose voice is childlike. He also wears a hat and carries a suitcase. Carrot is one of the random opponents and his special ability is to summon at minimum three small snowmen — one with a red scarf, one with a yellow snow cap, and one with a blue snow cap. They will freeze one or more columns of blocks in the opponent's field. Frozen blocks act like skulls until adjacent blocks are eliminated. Then they return to normal.
- Something about a Rose: When using her special ability, which is to raise vines from the opponent's field's floor, the outline of a rose sprouts from Crodia to signify her strength and high class status. Her emblem too is a rose.
- Staff of Authority: Courtesy of his priesthood, Doefsky wields a staff over twice his height that is topped by a cross. It is the source of his special ability, which is to remove all skulls from his own field.
- Suddenly Shouting: The protagonists have a habit of shouting whenever they have a strong reaction, be that telling Crodia that she can ABSOLUTELY NOT get abducted again, realizing they CAN'T USE THEIR SPECIAL ABILITY, or insisting that they're NOT OLD. Kiel in particular has a habit of raising his voice.
- Sword Beam: The two swordsmen, Kiil and Mikazuki, both utilize sword beams. During his special ability, Kiil unleashes a sword beam on his opponent's candle to cut it shorter. Similarly, when Mikazuki readies his special ability, which is to cut through the opponent's candle with his sword, he first draws a glowing ring around him with the katana's tip.
- Sword Lines: Once Mikazuki has unleashed his special ability's sword beam, the cuts inflicted on the candle are displayed through sword lines on the side.
- Trick Boss: Draqula is set up as the big bad that needs to be overcome. Instead, it is revealed that his abduction victim, Crodia, has already beaten him into submission and taken over his castle. Once Draqula has been defeated, she steps forth and refuses to return home with her supposed savior because she enjoys her new lifestyle. This prompts a final fight to convince her otherwise.
- Verbal Tic Name: The only sound Uga can make is "uga", for which he's named.
- Voluntary Shapeshifting: Ririan's magic wand allows her to take the shape of her opponent and use their own special abilities against them. She turns into an exact copy form-wise, but differs palette-wise from the original.
- Wingding Eyes: Any time a character has to react to something, shapes in the eyes indicate what the reaction is. Characters that incur a special ability get swirl eyes or cross eyes, happy characters get arch eyes, and Cyasarin on occasion has heart eyes
