So then, Archer MacLean's Mercury - another puzzle game for PSP. Is it as good as Lumines? Well, yes it is, but it's also completely different.

In a nutshell, Mercury sees you completing tasks by guiding a blob of mercury around various 3D mazes, tilting the mazes with the analogue pad to make the blob roll around various obstacles and objects, such as pressure switches. Like any excellent idea, it's simple, and like most good games it's an improved rip off of something that's been done before. Marble Madness was the first game all those years ago to place you guiding a ball around a maze, then Super Monkey Ball took this a step further with you tilting the maze rather than controlling the ball. So what's new?

As you're controlling a blob of mercury rather than a marble or, um, a monkey ball, your blob is unstable, gloopy and inclined to split. This adds a whole extra dimension to the formula and also makes for some interesting twists in the level designs. Some levels requite you to split your mercury into two pieces, then you might have to roll one of them under a spray booth, turning it red to then go on to activate a red switch, for example. What about if you start off with three different coloured blobs and have to activate three separate switches before trying to mix two of the colours together to form a new colour? With a range of varied elements thrown into the mix, Mercury successfully manages to take an already winning formula and improve on it so drastically that you wonder how on Earth nobody ever thought of it sooner; like the way your shield recharges on Halo - obvious when you think about it.

The puzzles that lie ahead of you are split into three types. There's Race, which puts you against the clock to solve the puzzle and finish it as quickly as possible. You can finish a race with the tiniest piece of your mercury left, as long as you're within the time limit. Then there's percentage, which is the opposite to race; you are given a lot more time to complete the maze but also have to retain a high percentage of your blob. Finally are the boss stages, which are a gruelling combination of the two.

Mercury is beautifully presented and each of the well designed, 3D mazes can be rotated and zoomed in and out of, which becomes an essential part of completing the mazes the further you progress. To start off with they're pretty straightforward, all on a flat area and you can easily complete them just by moving the analogue pad. However, as the game progresses you'll find yourself having to navigate your way around each side of a cube. A cube containing spikes that try to split your blob, conveyor belts to force it off the wrong way and awkwardly placed spray booths to make it the wrong colour. The soundtrack is well produced and sounds great, with nice, ambient tunes to keep you chilled out whilst playing, massaging your aching brain as you try to figure out what the hell is going on!

You see, this game really tests your grey matter and as you progress through the game, the problems that are posed to you can sometimes seem a million miles out of your capacity to fathom. This is where the clever bit kicks in. Rather than being overly frustrating in the difficult to play stakes, the game instead makes you think and analyse the problem. Usually once you've actually figured out what you need to do, it's not difficult or frustrating to complete the challenge; unlike Monkey Ball, which simply throws insanely tough, precision control levels at you in the later stages.

With over seventy levels and a multiplayer option, there's enough in Archer MacLean's Mercury to keep you going for a fair while. If you're a fan of puzzle games then this is a pretty essential purchase; you won't be disappointed. Even if you're not big into puzzle games, it might be worth a shot, as it's a great game to show off the PSP; the graphics and sound are lovely and anybody looking over your shoulder will be intrigued to know just what exactly is supposed to be going on.

Reviewed by Mark Hayhurst for AceGamez (All Rights Reserved).