People fear change. Especially within certain tried and tested genres. First person shooters, for instance, are one of the most holy of cows in gaming. Certain established facts aren't about to change anytime soon. When a gamer first picks up a shotgun, he knows what to expect and what situation to use it in. There is something to be said for this familiarity too, it certainly makes it much easier for new comers to pick up and play. But that's not what Metroid Prime 2 is about at all. It's not here to hold your hand or give you a shiny new gun, just when you need it. Metroid Prime is here to challenge you, so if you do fear change, turn back right now....

Metroid Prime 2: Echoes is the sequel to the criminally under appreciated (at retail, anyway) Metroid Prime, which was the first outing of Nintendo favourite Samus in a 3D environment. Retro studios did a hell of a job too, successfully translating Metroid's 2D feel into a beautifully realized world. This effect of using a 2D game as the influence for a 3D game cannot be understated, and working up from this template to build everything made it true to the original. Metroid Prime 2 sticks to this formula very closely, and though it initially may seem a little too much like an add-on pack, Retro's new ideas shine through very quickly.

The game itself is set on a world called Aether, where our heroine has crash-landed in an attempt to rescue some Galactic Federation marines. Aether is a world that has been split in two by a meteor strike many years ago, creating a dark and a light world, both fighting for ultimate control of the planets power. As Samus arrives, it seems the light side is about to lose this long battle. Kind of fortunate that a tooled up, power suited bounty hunter is ready to lend a hand, eh?

Rather than merely being an interesting story, the dark/light worlds are a critical part of the game play and it's this aspect that truly differentiates Echoes from its predecessor. The dark world is a caustic environment that changes the way you traverse it altogether. On open ground you will slowly take damage, unless you wait in the light of some useful crystals your allies have left around. It requires a whole different way of thinking and makes it a stark contrast from the light world. Though, in both worlds, backtracking and exploration are still familiar features, but this time puzzles require you to consider these parallel worlds in order to progress. This key feature affects every aspect of the game and makes something, which initially seems familiar, into a really interesting game world.

It's beautiful too. Again, the GameCube truly shows its abilities with Echoes; the wonderful detail of both worlds is incredible, creating a believable, living world. It's something that other developers seem to struggle with, but Retro handles it with aplomb. That's without even mentioning the creature designs. Everything has been crafted so well, with attention lavished on every creation; the Ing in particular are truly threatening foes, who come at you in many different forms, flowing and sliding around walls as they attack. They keep you on your toes, that's for sure.

One of Metroid's greatest strengths has always been the challenge though, and this certainly hasn't changed here. It's fiendishly difficult, and refuses to hold your hand at any point. Certainly, it sometimes points you in the right direction of a useful piece of equipment or the like, but this is rare. For the most part you'll have to figure out for yourself where to go next, and how to get past the next set of obstacles. This isn't something most gamers will be used to and it may put people off. On the other hand, it means that there is a great deal of satisfaction to be gained from making any headway. This sense of truly earning your progress is un-matched by any other game.

The famous morph ball is back as well. If anything, Echoes leans more heavily on this element than the first, with some very clever morph ball specific puzzles. Indeed Super Monkey Ball springs to mind on a few sections, though thankfully the game never reaches infuriating heights of that title. It's a great way to change the flow of the game also, and never seems jarring.

Echoes subverts the genre in even more ways too. One of the best elements of the game is the weapon set, or lack there of. In Metroid your starting weapon is your only weapon. It's your key, it's your rocket launcher, and it's your grappling hook. Which is good, as the damn thing is welded to your arm. The weapon system has been designed in such a way that this never feels stale though, with a variation of attacks all easily accessible. Your gun can also be modified and throughout the game certain power up's allow you to use, for example, the light beam, which is extremely effective against those damn Ing...

The use of varying visors is also superbly implemented and although very similar to the first Metroid Prime, it's still a great way to bring in new enemies and puzzles. It's this richness, all the elements in your arsenal slowly increasing that really makes the game so special. Each item adds another layer of strategy and opens other locations in every map. It's the ultimate game for any explorers amongst you. The scanning element is also a big part of this, allowing you to slowly uncover the story yourself in bits and pieces as you travel around this game world. Again, this may not find favour with everyone, but it's still an interesting way to tell a story. However, whether you want to scan everything or not, is entirely up to you.

Multiplayer is perhaps the games only disappointment

The multiplayer should be mentioned, but it is extremely disappointing and feels very tacked on. The control system for Metroid was never really designed for multiplayer combat and this is becomes evident very quickly. It also gives you immediate access to the toys you unlock throughout the single player game, which takes the edge off the discovery of them in the main game. On the whole, it's worth trying, but only after you've conquered the single player. Even then, it won't get much playtime.

If anything is apparent from reading this review it's that Echoes is very similar to the first Prime, and it's very difficult to ignore that. However, it was such a great formula, and with Echoes it has been refined and built upon to create a truly worthy sequel. Yes, it's challenging, but it's challenging in the very best way and it is a rare gem that reminds you just how great gaming can be. This game is not for everyone, and certainly won't convince the first games' critics, but anyone who has a fondness for the original will no doubt want to add this to their collection.