With so many puzzle games crowding the Xbox Marketplace these days, it's hard to separate the wheat from the chaff. You've got unoriginal Tetris clones, games too easy for most kids, and mechanics too awkward (or broken) to use effectively. Thankfully, SpiderMonk's recent puzzle game for Xbox Live Arcade avoids those fates. With elegantly designed and constantly evolving gameplay and a surprisingly high difficulty level, Roogoo is well worth playing despite its overwhelming cuteness and confection.

The core puzzle gameplay is surprisingly challenging.

As in most puzzle games, the story is nothing to write home about. You are helping these adorable big-eyed creatures called Roogoo to defeat the evil Meemoo, who are like Gremlin versions of the Roogoo, only they were transformed by greedily devouring meteors instead of eating after midnight. Well, the only way to defeat the Meemoo is to save the rest of the meteors from falling into Meemoo paws. After the intro sequence, you'll probably forget the story entirely until the closing credits, but this doesn't diminish the experience either way.

The premise is a straightforward game of fitting the square peg into the square hole; a game most of us played when we were toddlers. In Roogoo, shapes (the Meemoo's coveted meteors) fall from the sky as the player rotates discs so that the appropriately shaped hole lines up with the falling object. If the disc is lined up correctly, the "meteor" falls through to the next disc. Sound simple? Think again. At times, Roogoo is, in fact, infuriatingly hard.

In each of the game's 45 levels, new challenges and twists are constantly added to the gameplay: more shapes fall, the speed increases, discs flip around of their own accord, and a few surprising obstacles rear their ugly heads. The result is a constantly fresh, increasingly challenging puzzler. But the difficulty curve may also be the game's greatest downfall. With so many new elements constantly forcing you to reinvent your strategies, you can't possibly hope to master the gameplay in a single playthrough. The achievements that involve saving every meteor and beating the "par" times seem downright impossible until you've played each level a dozen times. On the bright side, the difficulty isn't a result of unwieldy controls, bad design choices, or cheap tricks; the challenges offered in Roogoo are designed to genuinely test your skill.

Thankfully, the game also offers a host of multiplayer options perfect for honing your Roogoo skills. Both co-op and adversarial play are fast and furious, and there is plenty of variety in the modes; playable by up to four players either locally or over Xbox Live. The multiplayer is a great party competition for casual and hardcore gamers alike. Admittedly, the fun could do with less interruption, as an inelegant matchmaking system makes it hard to play online with the same people for several matches in a row.

Sometimes, things just get a little too cute.

The visuals and sound are solid, if not stunning. Each level has a distinct aesthetic, while contributing to a unifying style: happy and adorable even in "scary" environments. Some of the effects in later levels are actually quite well done, including glowing lava and the ominous sound of steel slicing up your beloved meteor shapes. Overall, the graphics and sound never detract from the gameplay and, in many cases, improve the experience.

Roogoo is a good match for puzzle enthusiasts looking for a challenge. Both single player and multiplayer offer a surprising amount of depth and difficulty to keep you coming back for higher scores and faster times. For those less accustomed to playing puzzlers to perfection, expect plenty of swearing and aggravation, as the game hammers you with one challenging level after another. While there's a fiendish level of difficulty disguised in the hearts and rainbows, Roogoo offers just enough goodness to satisfy the sadistic puzzler in all of us.