Sometimes the greatest achievements come from the most adverse conditions. Take Metroid Prime for example. The task of taking Metroid into 3D was given to a relatively unknown American-based development house that, over the course of time, proceeded to lose staff, suffer production delays, get all their other projects cancelled and finally have Nintendo come in to rescue the project. The finished game should therefore have been completely lacklustre; however it happened to be one of the best games released for the Cube and a more-than-worthy addition to the Metroid franchise.

Samus' new mission is to investigate the planet Aether and locate a missing Federation ship and crew who were chasing some Space Pirates. All is not how it seems, as the planet Aether has recently been divided into two parallel worlds. The light side is inhabited by the Luminoth, who have been at war with the inhabitants of the dark side, the Ing, ever since. Upon meeting one of the last surviving Luminoth, Samus agrees to take on the mission of removing the Ing menace from the planet. There is also the space pirate presence to overcome, along with a far more serious threat waiting just around the corner...

The concept of planet Aether takes its cue from the duality introduced in the Zelda title A Link to the Past, in that both exist side-by-side and what happens in one world can potentially affect the other. The dark side happens to be a very nasty place, where the atmosphere corrodes Samus' suit and causes damage unless repelled by the light crystals the Luminoth installed during their battles. It is also responsible for Samus foolishly losing all her equipment AGAIN, and hence she must seek out and retrieve it from certain Ing beings that have taken one ability each. Naturally there are also some new toys to acquire, including beams using each plane's elemental essence. Unlike Prime though, they have limited ammo capacity and for once, some resource management issues have been introduced.

Metroid games live or die by their level design. Prime showed that the series could be taken into three dimensions and still keep the mystery, exploration and power-up acquisition system of previous games. Whilst the overall map isn't quite as large as Prime, the two worlds are completely separate entities and the dark side adds another 50% to the size of the game. Apart from place-markers such as save stations, each side is unique, being well built and cunningly constructed in the process. Actually negotiating some of the rooms is a mini-challenge all in itself.

Echoes continues the welcome trend of environments that look organic, feel organic, and wholly seem that they could really exist. Bountiful crags, jagged edges, spiralling trees and ponds teeming with life are commonplace. Even the smallest of plants sway in the programmed wind. The necessity of scanning remains, but thankfully now anything that has already been analysed shows up in green so you can see what may have been missed or changed. What you get for doing so is an incredibly detailed background insight, information into why all the factions are present on Aether, and the playing-out of a twisting narrative story when, on the surface, there isn't one to begin with.

The look and feel of Echoes, in a similar vein to The Matrix, is something that cannot be accurately described; it has to be experienced personally. The light side is vivid with life, full of verve and remarkable in its depiction of environment. The dark side is, naturally, evil - dark in colour, mainly a mix of purples and greys conveying the world that the Ing inhabit. So, why is the game called Echoes? One reason doesn't become clear until somewhere near the end when a specific power-up is gained. Turn it on and one of the most bizarre and uniquely weird visual effects greets your eyes, which also has some major gameplay significance in its own right.

For all this glory, however, Echoes starts off a little…well…slowly. Gradually though the game starts to show glimpses of its true quality, teasing you in and inducing that well-known gaming symptom, atemporality. By the time the third temple is revealed, you are ready to be slapped about with a large fish, Monty Python style, for it encapsulates just what a remarkable game Echoes is. The light and dark ethic works extremely well, and Retro have come up with some dual plane puzzles to rival that of its inspiration.

Echoes is not an easy game, either. The difficulty switch has been turned up another notch or two overall, and whilst several boss fights will take several attempts to finally master, there is nothing as wholly unfair as the Omega Pirate section from Prime. No such problems here, mercifully, though there will be plenty of scratched heads and overloaded brains whilst playing. Indeed, special note should go to the boss battles, as on the whole they are more inventive, clever and enjoyable than Prime. Anyone facing the Spider guardian should see that you can make a fight totally unique. The satisfaction from finally taking down one of these mothers is something players will remember for a long while.

One criticism of Prime was that there was too much backtracking, re-treading of existing locations and aimless wandering in the search of power-ups. Retro have obviously listened to these comments and afforded some improvements in the process. Levels are linked far more logically, meaning less trekking to get from one section to another. Power-ups are just as effectively concealed as before; the tricky part, as always, is figuring out how to reach them, and discovering just how deviously they've been hidden. Retro have listened to players' comments, and turned what made Prime a great Metroid title into something even better.

Not only is the game graphically superb, the audio is another notch above. Part of the problem with modern games is that the sound elements are often under-appreciated. Not so here. The ironic part is that because the sound in Echoes creates such an ambience with the action, for the most part you don't separate it as an individual element. It flows seamlessly into the game, changing tempo and style for each part of the planet with just the right mood at the appropriate time. For the most part outside of boss battles, the music is minimalistic but works perfectly for the loneliness of Samus' mission. Proof here that orchestral scores and dynamic opus-like compositions aren't always the best way forward.

The newly-added multiplayer game wasn't really needed in such a masterpiece as this, though it is a nice little addition tagged on. Sure, it won't rock the boat compared to such dedicated FPS as Halo and Timesplitters 2, but it is far from being pointless. Despite the fact the controls remain the same as the main game, the lock-on feature does not break it. Indeed, it only helps to keep you focused on one adversary, and doesn't mean an auto-hit with every shot you fire. Most weapons must be picked up and have limited ammo, meaning the equation isn’t overbalanced. Definitely worth a try out if you have some friends around to play.

So given that Echoes as a game is overall better than Prime, why isn't it scoring the same mark? Simply because it is no longer a genre defining piece of software. Prime laid the ground and rightly scored a maximum mark for its genius and quality; Echoes at its heart is merely Prime-plus. Whilst none of the levels quite match up to the stunning quality that was Phendrana Drifts, it is, as a sum of its parts, wonderfully evocative as a playing experience and induces the same level, if not more, of internal satisfaction that Prime achieved. It won't convert those who didn't like Prime, but then it was never designed to. It simply gives everyone who wanted more Metroid an even bigger helping of what they craved.