There's something timeless about those old labyrinth toys that tasked you with guiding a metal ball by tilting a maze. It's a simple concept that has translated well to video games as most famously seen with the Super Monkey Ball series. Taking the same concept and replacing "metal ball" with "blob of mercury," the Mercury games became favorites among puzzle game fans since the series debuted on the PSP many years ago. Mercury is about more than just hastily tilting a platform to make your blob flow from point A to point B; it forces you to think about the traps in your path and how the physics of your mercury blob can help (or hinder) your progress. This is no different for Mercury Hg, which brings a host of new levels to modern HD consoles, though it has lost some of the challenge and longevity in the transition.
The main goal in any Mercury Hg level is to tilt a mazelike platform with the left analog stick as you guide a blob of mercury (or more than one) to the goal. The catch is that you want to do this quickly and without losing any of the mercury that makes up your blob. The blob isn't totally cohesive, so if you get too close to an edge, you start to lose mercury as it drips down into an abyss. There are also many ways in which bits of your blob can split off from the whole, such as hitting the corner of a wall or landing from a fall with a lot of momentum. When this happens, you need to be extra careful with how you tilt the platform because it can be easy to send some bits off the stage while trying to guide other bits to the goal. In a pinch, you can hold a button to attract the blobs back together into a cohesive whole rather than try to force them back together with physics, but this ability comes at the cost of speeding up the clock, which you don't want to do when going for a high score or trying to beat a specific time. The PlayStation 3 version of the game features a Sixaxis control scheme that allows you to tilt the PS3 controller to tilt the level instead of using the analog stick. This feels natural and can be a fun way to play, but it also feels a little touchier and less precise than the default control option, so you may not want to use it for harder levels unless you're up for a tougher challenge.
The main game is composed of 60 discovery levels. Each of these has a total of four atoms for you to collect by fulfilling certain requirements: completing the level, finishing under the par time, finishing with 100 percent mercury, and collecting all of the pickups. These atoms go toward unlocking the later level groups, though there are far more atoms available than are required to unlock every stage, which makes collecting them less important if you merely want to complete each maze. Each stage has a par time of less than a minute or two, and some can be completed in mere seconds. But there's an addictive quality to the gameplay that makes you eager to hit "Next Stage" over and over again.
Most of these levels are pretty easy, perhaps to a fault. Many of the hurdles from previous Mercury games are gone, such as enemies and temperature puzzles. There are obstacles, such as magnetrons and anti-magnetrons, which try to pull your blob in or push you away, but most of your peril comes from the environment in the form of hills or holes. You often come across paint shops that change your blob into another color, which you need to do to activate certain switches or pass through certain walls. This gets particularly tricky when you need a secondary color such as yellow, but you don't have a yellow paint shop. You have to split your mercury into two blobs, paint one blob red and one blob green, and then combine them again to make yellow. It's a neat puzzle mechanic that should have been utilized more often to create more challenging levels.
By beating levels quickly and nabbing collectables, you can unlock challenge and bonus levels, which are where the difficulty really starts to ramp up. Bonus levels are the same as their discovery counterparts but with a different objective: You can't finish the level unless you have 100 percent of your mercury intact, and you don't start with all of it. So you have to carefully collect vials of mercury strewn around the stage while making sure not to lose even a tiny bit of it to one of the many obstacles. Challenge mode forces you to play several levels in quick succession, fulfilling certain requirements that get tougher as you move forward. For example, stage one of a challenge may require you to finish its three levels in under 120 seconds while collecting at least 10 pickups. Stage two may pit you against the same levels, but this time you only have 90 seconds, need 15 pickups, and can't lose a drop of mercury.
Mercury Hg has a nice aesthetic, with slick menus designed after the periodic table of elements and in-game graphics that feature clean designs with many vibrant colors. There are also a lot of neat stage effects like tiles that form in front of you as you move. Stage backgrounds react to the music being played as well, throbbing and pulsing with the beat. The included music is good, but you have the added bonus of playing the game with your own custom soundtrack, with the background being affected accordingly. It's not much, but it's a lovely touch and helps give life to the environment without getting in the way of the gameplay.
Playing through the discovery levels won't take you long, especially if you ignore most of the secondary challenges. The entire mode can be completed in a single sitting and never gets dreadfully difficult. You can add longevity to your experience by competing for higher leaderboard scores, which is made more enjoyable by the ability to download ghost data of top players to play against. You could certainly ask for more, such as some of the party modes from earlier Mercury games or more stages with more complex puzzles, but for a mere $5, it's hard to complain much. It may not fulfill all of its potential, but Mercury Hg is a fun game that will give you a few hours of enjoyment and can easily be picked up by anyone in the mood for a good puzzle game.