Aquapazza inspires low expectations. It looted its cast from the AQUAPLUS and Leaf catalog of visual novels, RPGs, and dating sims, all with narrow cadres of fans. It seems a fighting game made exclusively for those who follow AQUAPLUS creations, those who spent hours courting Tamaki Kousaka in To Heart 2 and yet more time unspooling the elaborate backstories of Utawarerumono. This suggests a simple and unmemorable thing, an over-sweetened confection that presents little gameplay depth while established fans button-jab their way through a storyline.

That would be completely wrong. In fact, Aquapazza is anything but simple.

The crossovers bloom rapidly in Aquapazza. An ineptly brewed love potion bursts dimensional seams and draws in schoolgirls from To Heart, tribal beast-folk from Utawarerumono, a gamut of fantasy archetypes from Tears to Tiara, and a smattering from Routes, Comic Party, Kizuato, and White Album. Their inevitable fights play out with a flourish; the characters are crisp, subtly well-animated sprites unleashing attacks that fill the screen with explosions, fireworks, and other glowing excess. The backgrounds are detailed pickings from the various series, with high-school backdrops, concert halls of waving cell phones, and a feast where a giant crab looks rather chipper about being boiled alive. All of this is backed by an upbeat soundtrack and constant exclamations from the combatants.

Beneath all of Aquapazza's adornments lies a pleasant surprise, for developer Examu built the game with a diverse and layered attention to fighting-game mechanics. The mage Riannon proves a predictably good zoner and the heroic swordsman Arawn gets an expected fireball-and-dragon-punch moveset, but others break from the norm. Archer Morgan induces different effects with her limited stock of arrows, pointy-eared ninja Oboro works in dashes and counters, and To Heart's Tamaki is, despite appearances, a grappler with enough suplexes and swinging throws to suit Zangief. The game makes the most of its three attack buttons, and even the routine moves get creative animations, such as Manaka's habit of throwing books—and bookcases—at her foes.

Aquapazza's thirteen playable fighters can join up with an equal assortment of partners, and there the game expands its depths further. All of the sidekicks are summoned by a single button and directional push, yet they offer different sorts of aid. Some heal, some immobilize the opponent, some just dive-kick, and, in the case of White Album's pop idols, some break into a damaging concert. When not fighting, they'll stand in the background to cheer the hits you give and wince at the ones you take, like team members in old installments of The King of Fighters. Why did The King of Fighters stop that? Oh well. It's good that Aquapazza started.

Other ideas drive Aquapazza, including an Active Emotion System that punishes dull matches. Block too much, and your character gets depressed and thus more vulnerable to Guard Crushes and other attacks. Keep up the pressure, however, and a happier fighter will gain more damaging super moves and tougher blocking methods. Borrowing another technique ignored by many other fighting games, Aquapazza has desperation moves in the form of Splash Arts. Once a character's life meter shrinks to the halfway point, he or she can pull off the fiercest special moves (and accompanying cut-scene animation) in the hopes of turning the tide.

Aquapazza proves a compellingly solid fighter, but it fumbles the one thing you'd expect it to do well: its story mode. Despite the tale's roots in dialogue-heavy visual novels, there's no real narrative here. Characters banter briefly, team up with whoever they meet, and keep everything decidedly inane. Compared to the likes of BlazBlue, Persona 4 Arena, or even the latest The King of Fighters, Aquapazza feels wan and underfed, with nothing to endear players to these characters and their possibly obscure origins.

Aquapazza only shows personality during the actual fights, in the detailed attacks and victory poses. Yet even there it demands a high tolerance for the sugary extremes of today's “moe” milieu. You're never far from the prancing, doe-eyed mannerisms of some schoolgirl, and it often overshadows the charms of the animation. Still, Aquapazza isn't as off-putting as it could've been. For a game based on some adults-only visual novels and developed by the panderers behind Arcana Heart, Aquapazza remains no more suggestive than the usual id-courting fighter. Impossibly proportioned women bounce around a bit, while Sasara switches costumes in battle and, much to her embarrassment, loses most of one after winning. But hey, she briefly dons a combat bikini from Golden Axe. That's a fun reference, right? Right.

How must a fighting game be judged? If it's solely a matter of intricacy, Aquapazza excels. It's complex and approachable, offering a good deal for the competitive enthusiast. Yet it comes up empty at heart, devoid of impressive style or interesting characters or any of the other supposedly trifling details that make good fighting games into great ones. Aquapazza goes deep as a fighter, but that's about all it does.