Archer Maclean's Mercury was an under-the-radar hit for the PSP last year, dishing out a unique and original game concept during a time when there wasn't a whole lot to choose from on Sony's powerful handheld, other than a bunch of remakes and slapped-together console ports. Although a solid puzzler and close runner-up behind Lumines in terms of overall quality and addictiveness, Mercury did have a number of minor shortcomings that hurt the entire package in the end, such as a frustrating camera, severe degree of difficulty and a rather pedestrian visual style. Now, along comes the follow up in Mercury Meltdown, which does everything a great sequel should do - it improves and evolves the gameplay mechanics without tampering with the core formula, jams in a smorgasbord of new game modes and features, upgrades the presentation and pretty much polishes everything else up to a glossy finish.

The main gameplay objective in Mercury Meltdown remains unchanged from its predecessor, with the game's whopping 160-plus puzzle trays (or stages) putting you to the task of carefully sliding a blob (or blobs) of mercury through various maze-like maps to a finish pad goal, while utilizing all sorts of clever contraptions, avoiding hazardous traps and hostiles, altering the mercury's color and keeping the blob as intact as you can, all under the pressure of a par time limit - think Super Monkey Ball and Marble Madness meets Rube Goldberg. The core gameplay may not have changed, but everything has been tremendously diversified. Puzzles now offer so many more different types of challenges and obstacles to circumvent. The mercury ball itself receives the most significant change, as there are now special State Changer nodes that alter the mercury's physical makeup, including Normal, Hot, Cold and Solid forms. When in hot form the mercury melts into a thin metallic substance that moves quicker and spreads apart easier, while the cold form slows it down but makes it much more viscous and tear resistant. Then in solid from the mercury melds into hard marble-esque ball.

As far as dangers and devices are concerned, Mercury Meltdown's puzzles are loaded as well. Schizoids and Mercoids hunt after your helpless little ball of metal and explode or chomp away from its form if they catch it, while Jacob's Ladders and Jerkoids use bolts of lighting to zap away from your mercury pool. Above and beyond that there are guillotine machines to avoid, swinging pendulums to sneak around, conveyor belts to ride, bridges to traverse, bounce pads to launch from, crumbling platforms to spring over and oh so much more.

If you think all of this sounds tough to handle on paper, just wait until you actually experience these puzzles for yourself! The puzzle boards are tricky and ingeniously blueprinted, putting every ounce of your brainpower and reflexive abilities to the test on a stage-by-stage basis. A detrimental flaw with the original Mercury was its unforgiving level of difficulty, but for the most part this has been remedied in Meltdown. Puzzle progression feels significantly better balanced, with the early stages starting off basic and each advancing stage and laboratory world growing steadily tougher as you progress. Unfortunately, it still lacks immediate pick-up-and-play accessibility due to a complicated (but much improved) camera system and realistic fluid physics that cause mercury movement to feel slippery and hard to control. To combat these issues, the game does help out by including a great tutorial, a cool playground stage filled with contraptions to practice on (almost like a skate park) and a free look option that lets you pause the game mid-stage to scout the map and plan your next course of action.

A brand new level structure has also been introduced to Meltdown, with accumulated scores and collected bonus items from each stage allotted towards unlocking new laboratories and puzzle stages (which can be completed in any order), special mercury skins and a nifty collection of five clever party games. These party games, which consist of fun activities such as shuffleboard, racing and a more conventional puzzle-type game of matching rows of colored blobs together (all with a Mercury twist of course), can be played solo or with a friend over ad hoc Wi-Fi, complimented by a two player Battle Mode, game sharing support and downloadable content (though no extra content has become available while I've been playing). All told, there's virtually unlimited replay value here.

To top everything off in style, Mercury Meltdown probably makes the most strides in the area of presentation. There isn't a whole lot in terms of audio to take in, although the bouncy music and arcadey chimes perfectly compliment the on-screen happenings, but Meltdown's graphics have taken a monumental leap forward from the first game. A colorful cel-shaded paint has been blasted onto every inch of the game's worlds and objects, displaying vibrant imagery, shiny surfaces and creative art design that sizzle on the PSP's widescreen with a lot of eye=catching flair and flash.

If puzzle games interest you even a little then you owe it to yourself to add Mercury Meltdown to your PSP collection. Its high level of difficulty could be seen as a flaw, making for a game that isn't as instantly accessible as classic puzzlers typically are, but the level structure is balanced enough to at least ease newcomers and casual players along gradually. Other than that I have nothing but adoring praise to lay upon this gem of a puzzle game - its colorful art design, addictive gameplay and treasure trove of modes and unlockable bonuses are simply to die for. Lumines may still be the undisputed king of PSP puzzlers, but Mercury Meltdown sure gives it a run for its money!

Reviewed by Matt Litten for AceGamez (All Rights Reserved).