It's a game you'll certainly want downloaded onto your PSP's memory stick for a drab 20 minute journey.
Building on the classic Marble Madness, Mercury is a game involving blobs of, well, mercury, and the guiding of them through increasingly difficult mazes. You'll need to split the mercury, change its colour, place it on switches and avoid enemies - sometimes all at once. Controlling a bit like SEGA's Super Monkey Ball, moving the PSP's analogue stick changes the poise of the stage and as such rolls the mercury about the level.
The game actually feels like the PSP was physically designed around it. The control is absolutely pin-point with the nub, and the camera control assigned to the Circle and Square buttons feels a lot more natural than you might initially think.
Whilst sounding conceptually simple, Mercury ramps up the difficulty quite early on. Each stage has unique pass criteria such as beating it in a certain time period or completing it with enough Mercury still in tact. The common theme is the scoring system which measures a bit of everything (the amount of your Mercury, the time you've taken, the number of switches pressed) and relies on perfect runs to conquer the leaderboard.
There are a number of worlds to play on and a real pile of levels within those worlds to complete. Unlike Monkey Ball, it's not deft control to the finish, this is a puzzle game foremost and that means you'll be headscratching your way through some of the game's worlds.
The graphics are fairly gorgeous, with a pseudo-cartoon look to the stages filling the PSP's screen with vibrancy. The soundtrack is also rather pleasant, sharing similarities with the sparse electro-house now so common in the PixelJunk games.
Mercury is fun in short blasts, and while it's not entirely the type of game you'll want to spend hours and hours glued to, it'll give you more than enough entertainment via frequent five-minute sessions.
Archer Maclean's Mercury is available from the Playstation Store now for just £4.79.