Etrian Odyssey 5: Beyond the Myth does a number of unusual things, but perhaps nothing about it is so remarkable as the way it showcases the strange duality of the 3DS’s twilight days.

On one hand, the platform is largely propped up by all-ages titles geared toward kids who have come into possession of 3DS systems as its price drops and their older siblings move along to livelier platforms. At the same time, however, you’ll also find a modest selection of unflinchingly difficult games geared toward seasoned players.

Of these, Atlus' Etrian Odyssey 5 may well prove to be the most unforgiving of the bunch. A great deal has changed with this latest Odyssey, but it remains faithful to key principles the first chapter of the series established a decade ago. Etrian Odyssey 5 hearkens back to the role-playing games of the early ’80s, when the genre mostly involved grueling dungeon crawls through winding labyrinths; and it relies on the dual-screen format of the DS/2DS/3DS family to make its demanding designs work.

From the beginning, the driving concept behind Etrian Odyssey has been to take the RPG concept back to its formative years. It calls back to the days before CGI cut scenes, Social Links and dialogue tree romance options redefined role-playing games as a story-driven format spiced up by occasional combat. Here, the combat breaks up exploration, not story. Plot in Etrian Odyssey 5 exists mainly for flavor, playing out in sparse dribs and drabs as you delve into a sprawling 30-floor labyrinth. Your heroes never speak for themselves; in fact, they don't even constitute proper characters. They amount to generic fighters that you build from the ground up from a pool of four races, 10 combat classes, multiple portrait selections and a handful of custom color palette options.

Most of all, Etrian Odyssey 5 calls back to the days before in-game auto-maps existed. Its immense dungeon spans dozens of floors, all neatly gridded, and the game demands you plot out your own map by hand. Yes, you can activate a rudimentary auto-map feature, but the going ultimately gets far easier (not to mention more satisfying) if you come up with your own personal code and standards for placing available icons to indicate the presence of hidden passages, resource-gathering points, and campfires for preparing food. The 3DS's stylus-driven lower touch screen becomes a stack of virtual graph paper once you enter the dungeon, each floor giving you a separate 35-by-30-square grid on which you can mark down the location of any and every point of interest you encounter.

In many respects, Etrian Odyssey 5 gives players enough rope to … well, if not hang themselves, precisely, then certainly trip themselves up. The map feature perfectly embodies the free-roaming, figure-it-out-yourself philosophy that drives the adventure. You're given a huge palette of icons and color tools to use, yet you're offered only the most rudimentary explanation of how you're meant to map the dungeon. As someone who cut his teeth mapping 8-bit games on graph paper, I relished the challenge of coming up with my own visual code for my labyrinthine forays, though I can see where others might find it a daunting or tedious requirement.

The in-game map offers features that would be impossible on actual paper (such as dynamic real-time tracking of F.O.E.s, the deadly wandering mini-bosses that populate the dungeon), and you can collect rewards and shortcut features in return for plotting out an entire floor. But for the most part, the pioneer spirit of Etrian Odyssey 5 leaves you to your own devices … just like in the olden days.

Etrian Odyssey can be esoteric, lacking the broad appeal of something like Pokémon

The game offers a similar lack of guidance when it comes to combat, and even for building parties. From the outset, you have access to an enormous array of battle options and information, as each party member presents you with two different skill trees (one class-specific, one race-specific) to be fleshed out as you earn experience. You can deduce the general role of classes by reading through their upgrade options, but the true value of many classes here — especially the ones completely new to this sequel, like Necromancer and Rover — doesn't become truly evident until you unlock their capabilities and experiment with them through real combat.

Etrian Odyssey 5 starts complex and gives you even more to chew on as you advance. Once you complete the second stratum of the dungeon, you unlock prestige subclasses for your team, allowing each party member to hone in on a specific area of their basic class. Classes are normally tied to specific character races, but truly dedicated players can rebuild team members into custom setups that would be impossible by default. It can feel overwhelming, even for a veteran like myself, who’s spent hundreds of hours with the series. To its credit, though, the game bends over backwards to provide all the data you need to make smart choices for both big-picture team-building and moment-to-moment battle tactics. Etrian Odyssey 5 can be esoteric, lacking the broad appeal for something like Pokémon, which hides its min/max-focused meta-game beneath a simple adventure geared toward casual players. But if you want an RPG that lets you dig into the nuts and bolts of its systems from the outset, you really can’t beat Etrian Odyssey 5.

The game also offers tools to mitigate inevitable poor decisions. You can sacrifice experience and character levels in exchange for a chance to rebuild a warrior from scratch — something that may be necessary if, say, you reach the first major boss and discover you don't have the group-healing capabilities you'll need to weather the battle, or if you realize upon encountering the second stratum's boss that you should have invested more skill points into your Dragoon's ability to shield the party from elemental attacks. This adds up to a difficult and sometimes daunting take on the RPG, but that friction helps reinforce the sensation that you, the player, have assumed the role of a pioneer setting off into unknown lands. It's supposed to be a deadly trek fraught with peril: The Oregon Trail, but with cosmic super-bosses killing you instead of dysentery.

For long-time Etrian fans, this fifth adventure feels like a genuine refresh of the series as opposed to the usual incremental revision. It abandons the vehicle-based overworld mapping of Etrian Odyssey 3 and 4 in favor of a single, interlinked, 30-floor/six-stratum dungeon, akin to the first two games. However, the internal workings of the dungeon have never felt more varied. Where the environments in previous games amounted to visual wallpaper over top of generally identical corridors, here the dungeons vary in nature from floor to floor. A tightly wound set of interlocking passages can give way to immense open spaces, and you'll find the path broken up by ravines and pools of water that lend the sensation of an open environment despite being divided up by functional barriers.

More importantly, there's more to do while exploring. In-dungeon events appear constantly, and they range from chance encounters with other guilds, to taking risks in order to retrieve precarious resources, to collecting rare beetles that you can pit against a bug fanatic's prize stag beetle. Even better, the outcome of these events no longer boils down to whether or not you happen to guess the right answer; most outcomes depend on the various race-specific abilities you can invest skill points into. A run-in with a frightened beast will play out differently if you've taken the time to give a party member an affinity for handling wild animals than if you haven't. The frequency and nature of these text-driven scenarios make Etrian Odyssey 5 feel more like a proper pen-and-paper gaming session than any other console RPG I can think of, and it really helps reinforce the old-school vibe hinted at by the in-game mapping mechanics.

I also can't say enough good things about the new monsters in this sequel. They may not look as nice as the creatures that populated previous Odyssey games, but what they lack in aesthetic appeal, they more than make up for with interesting combat mechanics. For example, the first stratum combines seemingly harmless monsters in dangerous ways; the lowest-level monsters in the game pose little threat on their own, but one enemy type can devour them to boost its own stats. An even more advanced creature can fling those smaller monsters at the party for a group attack powerful enough to result in a total team wipeout if you're not careful. Meanwhile, the second stratum largely revolves around spatial puzzles, in which you have to evade and outwit F.O.E.s capable of using the environment against you in various ways, while the third challenges you to manage environmental hazards that vary wildly according to the time of day.

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Etrian Odyssey 5 is a refinement of the series’ — and genre’s — best qualities

While Etrian Odyssey 5 may not be well-suited for genre novices or people who shy away from the combat side of RPGs, you'd be hard-pressed to find a stronger example of this particular slice of the genre. It offers enormous customization; fresh challenges both inside and out of combat; a setting rich with things to do besides simply fight; and best of all, that addictive mapping feature. Here's a game destined to appeal to the lizard brain of Type-A personalities, to people who love to line up details and see everything slowly take shape. With each line you draw on the in-game map, you bring a tiny bit more order to chaos and transform the unknown into the familiar. Etrian Odyssey 5 isn't simply the best game in its own franchise, it's easily the richest and most satisfying dungeon crawler to appear in the past decade.

Etrian Odyssey 5: Beyond the Myth was reviewed using a final “retail” Nintendo 3DS download code provided by Atlus. You can find additional information about Polygon’s ethics policy here .