Since its début back in the DS days, ATLUS' Etrian Odyssey series has been well-represented in the West, with every main entry, an ongoing run of 'Untold' story-driven remakes and the magnificent mashup Persona Q all making their way to eager European and American gamers. The Mystery Dungeon games - while equally well-known in Japan - are less established outside of their homeland, and perhaps most familiar to Western players through their crossover efforts; chances are those who've embarked on one of Chunsoft's classic roguelike adventures did so accompanied by either Pikachu or a Chocobo. Happily, 3DS owners have a new reason to get acquainted with both of these RPG giants, thanks to ATLUS' latest crossover title which combines the two into an excellent epic of exploration: Etrian Mystery Dungeon.

The story setup for Etrian Mystery Dungeon is very slight, although for being the combined product of two series traditionally lacking much in the way of pre-packaged narrative, it's actually relatively engaging. The tale centres on the town of Aslarga, situated in the picturesque shadow of the enormous Amber Yggdrasil tree. Thanks to the shapeshifting 'mystery dungeons' that dot the surrounding landscape, Aslarga attracts a huge number of explorers hoping for a piece of the glory. Fortunately, the townspeople are happy to host this parade of well-armed adventurers, primarily in the hopes that they'll protect the town from a foretold 'Day of Reckoning' - and that's where you come in.

As a promising adventurer newly arrived to Aslarga, it falls to you to save the town from its unspecified fate, and to do that you'll need to hop onboard a Skyship and head for the dungeons, where the experience proper begins. Leading a four-person team of adventurers you create yourself, you'll comb your way through multistoried, randomly generated labyrinths, beating up monsters and picking up loot en route to the bottom, where - if you manage to make it - a battle with a hugely powerful boss awaits. More often than not, you'll have to make several passes at a dungeon before reaching the boss - though auto-regenerating HP and TP-restoring Amber tiles help you last longer underground - and the basic gameplay loop revolves around pushing your team to explore just a little bit further each time, gaining experience and gold before popping back to the surface and doing it all again.

Back in the menu-based town, you can avail yourself of the services of several familiar Etrian outfitters, including an inn for rest, recovery, and item storage, a restaurant for accepting the many optional - and interesting! - side-quests, an Explorer's Guild for managing your party and creating new characters, and a shop for selling materials and grabbing new gear before you head back into the dungeons.

So far, it sounds like any Etrian Odyssey adventure; but Etrian Mystery Dungeon actually plays much more like a Mystery Dungeon game with an Etrian-inspired coat of paint than the other way around. In fact, in terms of on-the-ground gameplay, it's far closer to Pokémon Mystery Dungeon: Gates to Infinity than Etrian Odyssey IV: Legends of the Titan. Abandoning the first-person viewpoint found in the mainline Etrian games, Etrian Mystery Dungeon is played from a top-down perspective, with grid- and turn-based movement and actions alike. Exploration and combat are both taken step-by-step, and there's no distinct 'battle screen' to speak of - skirmishes take place right on the dungeon floor, and placement and positioning correspondingly play a huge role in battle. Because of the on-field combat setup, the traditional command menu takes a backseat; instead, holding down 'L' brings up an overlay of button shortcuts for up to six of your character's skills.

It's worth noting that that's singular 'character', too; in the Mystery Dungeon tradition, you'll only directly control one of your party members - known as the Leader - while the other three are controlled by the AI. For the most part, this works very well; computer-controlled fighters move and attack intelligently, and only very rarely end up skipping the wrong way down a hall after some wayward foe. It can occasionally be frustrating to not have final say over what your secondary characters end up doing - they tend to use up TP faster than we'd like, for instance - but overall we enjoyed the streamlined feel of leading by example. The game also builds in several ways for players to micromanage if they so choose: you can switch Leaders at any time, special 'Blast' skills allow you to issue orders to or control everyone in the party for a limited time, and in the boss battles - tough, engaging fights that require expert coordination between your team - you'll always have complete control over each character.

More Mystery Dungeon mechanics include an auto-map that fills as you explore - there's none of the DIY cartography from Etrian Odyssey here - a 'Food Points' (FP) meter to keep track of, which limits the number of steps your Leader can explore for without recharging with some tasty Bread or by walking over Amber tiles, and, of course, plenty of traps. Hidden throughout the labyrinths, these pop-up snares can cause status effects like Sleep or Confusion, deal damage, or fling you unceremoniously across the room, all of which add to the 'Mystery' feel of exploration and encourage a cautious respect for your surroundings.

Of course, there's a reason 'Etrian' is in the title, and the gameplay in Etrian Mystery Dungeon takes plenty of influence from ATLUS' delightful dungeon crawlers as well. The most obvious nod to that series is in the class system - a big part of the fun of the adventure comes down to the fact that you create the cast yourself, and you'll have plenty of characteristically distinctive options to choose from when designing your party.

There are ten classes in all, including RPG regulars like the magic-casting Runemasters, healing Medics, defense-heavy Protectors, and Landsknechts - dependable, delightfully-named sword-swingers. More fanciful occupations include the fleet-footed Ninjas, curse-flinging Hexers, long-distance Gunners, buff-happy Sovereigns, and the Dancers - Etrian Odyssey's signature, sambaing support class. Finally, the Wanderer - whose heavy-hatted design is a nod to Mystery Dungeon's most famous main character - rounds out the cast as an exploration-focused jack-of-all-trades. Each class comes in both male and female versions with four colour variants apiece, all with beautiful character portraits in the anime-influenced style of Etrian Odyssey IV, and seeing them come to life as chibi 3D models is a real treat.

As in Etrian Odyssey, every character you create has access to a wide range of unlockable and upgradeable Skills, including attacks, defensive enhancements, healing spells, buffs and debuffs, and more. They tap into classic Etrian abilities, like follow-up Links, and Binds which target specific parts of enemy anatomy, and make for deep, strategic combat - incapacitating a foe's arms, legs, or head can turn the tide in a tight spot, for instance, while crafting a multi-hit train of attacks through clever use of Links is always immensely satisfying. Extra-powerful, class-specific 'Blast' skills also become available as you play, and allow you to unleash field-sweeping effects once you've saved up enough meter through continued combat.

The multi-level Skill Trees are deep and surprisingly diverse, so whether you want a Landsknecht focused on pure offensive power or debilitating debuffs, you can make it happen - though a handy autofill option makes this an optional part of the experience. Figuring out optimal party combinations with your customized characters is a blast; the classes are smartly designed to work synergistically, and coming up with bespoke strategies for different situations makes for satisfying, strategic fun.

Our only complaint is that, with all the class variety on offer, four slots in the party just doesn't feel like enough. The traditional five-person parties in Etrian Odyssey games gives players plenty of space for wild cards, but here, there's less room for experimentation; in fact, with a Medic pretty much mandatory for most expeditions, you've essentially only got three slots to get creative. It's not that four characters doesn't make for workable or exciting teams - the traditional melee, long-range, healer, and magic combo is easy to pull off, and we led one memorable (and successful) dungeon run with a party of two Dancers and two Ninjas - but simply that the classes are so enjoyable to experiment with that we would've liked to try out more at once.

On the flip side, a benefit of the four-person parties is that crafting your crack team becomes a fun challenge in and of itself - a very good thing, because you'll need to take party composition seriously in light of the game's difficulty. Perhaps predictably considering its lineage, Etrian Mystery Dungeon is a tough game; enemy level spikes start early and come often, boss fights are long and vicious, and - as is standard in Mystery Dungeon games - getting wiped out will send you back to town with all your cash, items, materials, and various pieces of equipment conspicuously absent. Though you'll eventually be able to send in rescue teams to recover your fallen adventurers, it's never a guarantee, and it makes Game Over screens considerably more meaningful than in most modern games - and an unskippable auto-save before each trip to the dungeon even seals your fate beyond the help of save-state abuse. Whether the challenge is a selling point or a strike depends on the player, but it's worth noting that it's the only way here; there's no equivalent of the 'Casual' difficulty levels in recent Etrian Odyssey games to take the sting out, and it's considerably less accessible as a result.

Speaking of challenge, it's provided incarnate in Etrian Mystery Dungeon's DOEs - Dungeon-On Enemies - the game's twist on Etrian Odyssey's traditional fearsome FOEs. Once these massive monsters invade the labyrinths, you'll want to stay well clear - at least at first - as engaging them prematurely almost always spells single-turn death for your party. Dealing with DOEs is a little more involved in Mystery Dungeon than most Etrian games, too; rather than simply stay out of their way, you'll have to ensure they don't make it up out of the dungeon to invade the town by building Forts.

You can create a Fort on any floor you've previously explored, and doing so will both lock the dungeon layout in place - so it won't be re-randomly generated the next time you enter - and act as a barrier to any DOEs creeping their way up. You can stock the fort with reserve team members from your Explorer's Guild if you like, and once a DOE reaches its floor, it will either trigger a switch to a battle using your defending team, or - if the Fort is unmanned - destroy the structure and sink back down into the depths. Forts add a welcome extension of the adventure beyond your immediate party, and though at times it can feel like a bit much to manage, it's still a nice mashup of Etrian's FOEs with a Mystery Dungeon twist.

In fact, most of Etrian Mystery Dungeon feels like an excellent mix of its two halves. It incorporates systems and sensibilities from each series, and though in basic gameplay it leans more towards the Mystery Dungeon side of things, fans of either will feel right at home here. Unfortunately, that also means that those few parts of the experience that don't quite mesh stand out all the more.

One such problem comes with the use of Skills. From healing and buffing to defense and spell-slinging, Skills are a huge part of the gameplay, and you'll rely on them constantly throughout your adventure, during which time it will quickly become apparent that Etrian Odyssey's intricate skillsets were made for menus, not Mystery Dungeon's button commands. You can assign individual Skills to combinations of 'L' and three of the four face buttons and D-Pad directions, giving six shortcuts for each character - and while that's certainly sufficient in early days, it's easy to run out of room even midway through the Skill tree. Worse, it's also surprisingly easy to get confused; in the heat of battle - and especially in boss fights, where you're suddenly switching to a new character each turn - trying to keep every combination straight can put a damper on the momentum and rhythm of combat. The shortcut system works well in Pokémon Mystery Dungeon, where you're limited to four attacks on the face buttons, but here, juggling six equipped Skills along with several more unassigned and potentially useful abilities can be a bit much to handle.

The other issue concerns the dungeons themselves. The fact that they're randomly generated - a defining feature of the Mystery Dungeon series - should ostensibly translate into nearly endless variety, but in practice it means that each floor is almost entirely unremarkable. The narrow set of snap-to-grid building blocks used to generate every level - single-space-wide corridors and rooms of more or less similar sizes - becomes transparent very quickly, and rather than infinite variety you're left with endless déjà vu. It's particularly problematic since the crossover invites direct comparison to the mainline Etiran Odyssey series, where thoughtful dungeon design and clever set-pieces make the labyrinths themselves highlights of the experience; the design-by-RNG catacombs in Etrian Mystery Dungeon simply can't live up to that legacy.

Happily, even if Etrian Mystery Dungeon's mazes aren't especially memorable, they're still absolutely beautiful; this Mystery Dungeon inherits Etrian Odyssey's eschewal of drab dungeon-crawler aesthetics and goes for green over grim to wonderful results. Labyrinth names like 'Pristine Stream' and 'Emerald Copse' give an idea of the idyll on offer, and the visuals follow through completely - lush overgrowth, gently flowing streams, and canopy-filtered lighting effects all combine to create singularly appealing environments. The character portraits look great too, and the in-game models do a nice job of transferring that personality to polygons, while visible equipment changes add a nice touch to the customization process.

Elsewhere the presentation is less polished; the framerate can stutter distractingly when dashing, and the stereoscopic 3D effect suffers from particularly finicky, jumpy layering. The interface can also be obtuse at times - it's easy to descend into multilayered menu hell - and the top screen feels unnecessarily cluttered, with character statuses, a wordy running log of every action taken, and menu overlays all crowding the view.

The soundtrack, however, is fantastic from start to finish. Like the visual presentation, it takes after the Etrian side of the equation, with gently lilting orchestral themes that set the tone for exploration perfectly, both serene and slightly unsettling in turn. Boss battles are accompanied by more immediately epic, heart-rate-raising arrangements, while the sound effects and menu chimes come straight from classic Etrian Odyssey games.

Conclusion

Wrapping Mystery Dungeon' time-tested gameplay in an evergreen Etrian aesthetic, Etrian Mystery Dungeon is another excellent RPG in the 3DS' already impressive lineup. It's not always a perfect mashup - the randomly generated Mystery dungeons aren't a patch on Etrian Odyssey's memorable mazes, and the elaborate skillsets feel better suited to menus than button mappings - but the masterful mix of addictive exploration, strategic combat, extensive customization, and a real sense of adventure remains engrossing throughout. Fans of either series - or anyone up for a challenging dungeon-crawl in a idyllic setting - will have a great time combing through these charming catacombs.