It's always hard to follow on from a hit game - and it's even harder to follow on from a game like Portal. Bringing with it a charming mix of humour, a simple concept, and some devilishly tricky physics based puzzles, Portal was a game that garnered a huge following, thanks in no small part to being so utterly original. Based around a single, ingenious concept, Portal gave you a gun with which you could make two portals, that connected two points of the room together - walk through the one portal, and you'd appear in the other. It was a simple enough concept, yet it lent itself to countless possibilities - as Portal adequately demonstrated, as no two puzzles ever played out the same. Quantum Conundrum, out now on the Xbox Live Arcade, PS3 and PC, is a sequel of sorts to Portal, as the brainchild of one of the game's main designers - and the similarities are easy to see. A physics based puzzle game? Check. A disembodied voice providing direction as you explore a strange facility? Check. But is it just as good?
The idea behind Quantum Conundrum isn't quite as simple as the one behind Portal - although it does still have something to do with physics. Playing as an unnamed relative of crazy professor Fitz Quadwrangle, you arrive at the kooky Professor's mansion, ready to stay the night, only for one of the Professor's experiments to go wrong. Prof Quadrwangle then ends up getting trapped in another dimension - and, as you may imagine, it's up to you to get him out. Guided by the Professor's voice, you'll explore the various wings of the mansion, putting right the various experiments that are going wrong in each room by making use of a special "glove" that lets you jump between different dimensions. And it's this that's intended to be the mega-clever twist.
By pressing a button, you can switch between alternate dimensions at any time - but rather than everything being different in each alternate dimension, instead, only the properties of the objects change. The four available dimensions are the fluffy dimension, which makes everything light; the heavy dimension, which, well, you can probably guess; the slow dimension, which makes everything move more slowly, and the reverse gravity dimension, which lightens gravity for every object in the room, bar yourself.
And while it may not be as simple a concept as Portal's portals, Quantum Conundrum's dimension shifting is certainly put to good use. Each of the rooms you come across in the mansion contains a puzzle that must be solved, usually under the guise of a malfunctioning machine, or a switch in an inaccessible area that somehow needs to be pressed. Solving them ranges from the fairly straightforward, to the incredibly complex. One of the early puzzles see you having to smash a glass window to get at a switch behind it. With a safe sitting on the ground next to you, all you have to do is switch to the fluffy dimension, pick up the safe with the X button (the fluffy dimension makes the safe so light you can happily pick it up), and chuck it at the glass window, switching back to the normal dimension just before the safe makes contact with the glass, at which point the safe regains its normal weight, and smashes straight through. Some of the trickier puzzles later on require you to make use of giant fans to build bridges in the fluffy dimension made out of crates. Faced with a giant chasm in between the platform you're standing on, and the platform you need to get to, the only other thing in the room with you is a giant fan built into the one wall, blowing a gale at you from your right hand side, and a few crates. In order to make it across, you'll need to pick up these crates one by one in the fluffy dimension, and drop them into the chasm, where the wind from the fan will take them, and force them against the wall, holding them in place, letting you construct a makeshift bridge. It's hard to talk too much about these puzzles without giving too much away, but needless to say, there are countless ways you'll have to make use of the various dimensions in order to progress through the game.
And it's in the experimentation, and the problem solving, that Quantum Conundrum starts to shine, as few of the puzzles can simply be aced first time. Upon entering a room, you'll have to stop, look around, and explore every nook and cranny before you even start to try and solve the puzzle, as having a mental inventory of the objects you have available goes a long way to helping you solve each challenge. One of the more intricate puzzles sees you having to stick a set of reactor cores into a number of large, towering vats, which are suspended above a bottomless pit. In order to get the cores into the vat, all you have to do is chuck them, like a basketball, towards the top of the vat - if you're lucky, they'll bounce around the rim, and drop down inside. But it's how you go about chucking them that's the interesting part. With the vats suspended well above human height, even jumping won't get you high enough - instead, you'll need a cunning plan.