Intergalactic bounty hunter Samus Aran is back and, while it's debatable whether she's better than ever, she's certainly doing what she does better than anybody else.

Series fans can breathe a sigh of relief as, after a few bizarre missteps and some long gaps with no Metroid at all, Samus Returns is up there with the best the games have to offer.

For the uninitiated, Metroid is Nintendo's most complex franchise, and possibly its most often overlooked, despite the massive influence it's had on many of today's most beloved games. The series is all about getting lost in subterranean worlds, finding your way forward while frequently hitting dead ends and inaccessible paths.

But the world is littered with hidden items, upgrades and abilities, with each allowing Samus to overcome a particular kind of obstacle. Soon you realise that all those dead ends were not so dead after all, resulting in a satisfying loop where your exploration is not only rewarded with a path forward, but with access to areas you previously passed but couldn't get to.

Returning to an old-school, side-scrolling perspective after the series' reinvention as a 3D first-person blockbuster in the early 2000s, Samus Returns is the first game in more than a decade that fully commits to this central Metroid idea, making the game's title very apt indeed. Bombing through walls to find hidden paths, crawling around in Samus' morph ball mode, and experimenting with each newly unlocked ability is as exhilarating as ever, and a handful of big upgrades that totally change the way you play mean the game stays fresh over its dozen of hours or so.

Narratively, Samus Returns supplants the 1991 Game Boy game Metroid II, but besides the story and the general shape of the map this is an all new adventure.

Our bounty hunter has been tasked with the total eradication of the metroids — a species of rapidly-evolving, vicious parasites that space terrorists plan to weaponise — which have dwindled in number to just 40 creatures. With no dialogue or hints to speak of, it's up to the player alone to map out the planet SR388's network of structures and locate ancient artefacts that can augment Samus' weapons and suit, as her genocidal mission takes her deeper underground.

One thing the game has retained from Metroid II is the conceit of having to hunt and kill all 40 metroids, which is a very different goal compared to other notable games in the series. Consequently the structure is a bit more modular than series fans might expect, with new areas opening up not because of some narrative conceit or new special power, but once you've killed a requisite number of creatures. It's unusual, but it suits the portable nature of the game.

While the planet overall has a poisonous, inhospitable vibe, the individual areas are surprisingly diverse, at least aesthetically. Plants flourish in water-filled underground reservoirs, while deeper still the air is filled with golden dust from the churning and pounding of ancient machinery. Areas are cleverly designed to be vastly different depending on how powered up you are when you visit them. Not only do new abilities give you access to new spaces, they also offer shortcuts or enable you to fly through rooms that required meticulous, careful traversal previously. The satisfying, empowering design work sets the game well apart from its Game Boy inspiration.

The last time the series went back to revitalise a past entry was 2004's excellent Zero Mission, which remade the very first game in the style of series high-point Super Metroid. By contrast, while Samus Returns definitely aims to be a modern Super Metroid, it also adds a heap of new features that make this a faster, more responsive and more accessible game, even if they also make it feel a bit less focused.

Samus can now point and shoot smoothly in a full 360 degrees, also packing a new melee attack that keeps enemies at bay and primes them for a follow-up kill shot. These new mechanics — combined with smart touch-enabled maps and weapon management — make this the most modern-feeling 2D Metroid, letting combat flow much more naturally, but they also introduce a handful of awkward moments where you're expected to jump, aim, shoot and melee in combinations that the human hands just don't seem designed to accommodate.

One of the most contentious additions is the Aeion system, which lets you collect power from enemies and use it to power four special abilities. The first two you'll find are Scan Pulse, which fills in the map in a large area around Samus, and Lightning Armor, which negates damage. Since mapping and staying alive are both important, managing this one pool of Aeon is tough early on. But it doesn't feel unfair, since you can choose to map manually and use the armour to stay safe, or play defensively and use the scan to plan routes. The biggest issue here is that overusing the scan — which also highlights hidden paths — will rob you of that classic Metroid excitement when you figure something out.

The common thread with all my gripes about this game is that modern touches have been implemented to smooth some of the rough edges of the game's older inspirations, but those touches have introduced some niggles themselves. Another example is the new checkpoint system, which means you no longer risk losing an hour of progress if you take on a boss without returning to a save point first, but also introduces uncertainty and a false sense of security since there's no way of knowing when a checkpoint is triggered. 

This might be the final big game for the 3DS platform, but Samus Returns pushes the aging hardware to the limit with detailed 3D backdrops impeccable animation. Samus in particular looks great, the very picture of a stylishly efficient killing machine as she tracks an enemy back over her shoulder, or adjusts her aim and absorbs the recoil of a blast with her shoulders. The game's brilliant musical score deserves a mention too, combining sombre original tracks with updated Metroid II orchestrations and some incredible Super Metroid covers.

Despite some growing pains with the new additions to the formula, I couldn't really be happier with this effort to bring the ever-relevant Metroid series back into the mainstream consciousness. Everything great about Zero Mission and Super Metroid is here, albeit with a modern flavour, and it's probably the ideal way for series newcomers to jump in. Nintendo has already announced it plans to continue the 3D Prime branch of the saga as well, but Samus Returns is an excellent way to showcase the specific strengths of the more traditional side-scrolling style.

Metroid: Samus Returns is out for Nintendo 3DS on September 16.