Mercury Meltdown is the sequel to one of the PSP's launch titles, Archer MacLean’s Mercury and this title improves upon the already excellent formula.

Where the original Mercury opted to go for a very realistic style (or as realistic as a blob of silver goo on floating platforms can be), Meltdown went with a more stylized, cel-shaded format in order to make the game a bit more appealing to the general public. This graphical overhaul is probably the most noticeable difference between the two games since, for the most part, the gameplay and game mechanics of Mercury Meltdown are the same as before.

The game's audio is as similar to the previous games as the graphics are different. While playing through this game, I made a point to dust off my copy of the previous title and refresh my memory on how it sounded. Though the games don't use the exact same musical score, it is obvious that the developers didn't try to stray too far from the audible style set by the first game.

Like its predecessor, Mercury Meltdown has a Marble Madness style gameplay where you tilt the level in order to manipulate one or more blobs of mercury to the finish line. Along the way, you will have to split your mercury into multiple blobs and change the various parts into particular colors (and maybe even recombine them to form other colors) to get your mercury into the right states when you reach the finish line.

Where Mercury Meltdown's gameplay differs from the last game is that now you have to worry about your mercury's physical state along with its colors. The four states your mercury can become are normal, cold, hot and solid.

Normal has the blobs behaving as we would expect them to from the last game. The solid state forms the mercury into a hard ball bearing that makes it possible to ride along rails. The other two states, hot and cold, affect not only how fast the mercury moves (cold being slower and hot faster) but also how well it stays together. For instance, while mercury blobs in a hot state move faster, they are looser and tend to fly apart a lot easier.

With these changes, not only do the game's singleplayer puzzles receive a new dimension of complexity, but the multiplayer actions are also given a boost. In Battle Mode, each player will go through a particular level independently of the other, but pickups you find along the way either benefit you or hinder your opponent. One such pickup, Reverse Controls, does exactly that, switching your opponent's control scheme and forcing them to have to rethink on the fly. And another pickup turns your enemy's mercury into the cold state so that they move slower. Another multiplayer game, Rodeo, lets you see how long you can keep your mercury on a small platform with fans blowing all around.

Mercury Meltdown's difficulty is set at about the same level as the last game. The game slowly introduces you to mechanic after mechanic (aka enemies, conveyor belts, grav benders, etc.) and slowly builds you up into more complex puzzles.

The last game offered you a stair step level progression that, while giving you choices on what order to attack levels, forced you to take on all levels before advancing to the next world. But in this game, you only need to complete a certain percentage of each world which helps to alleviate some of the painful parts of Mercury.

Mercury Meltdown is one of those simple to learn, hard to master games that are so addictive. The controls are simple; use the analog stick to tilt the level and guide your blobs of goo to the finish area. Levels start off straightforward and simple with few pitfalls, but it isn't long before you are doing some crazy balancing acts while avoiding electricity-shooting Jacob's Ladders or mercury-munching mercoids.

Mercury Meltdown is a good example of what a sequel should be. It keeps the core mechanics that made the first game so addictive and fun and builds on top of it another layer of complexity to keep fans of the first game even more challenged. But it is a game that is geared towards people who played the last game -- I'm not entirely convinced that this title's tutorial will help complete newcomers jump right into this game. If you haven't played Mercury, I would definitely recommend renting or buying it before picking up Meltdown.