Despite its appearance to the contrary, Itatake and Hello There's cute puzzler 'Pebble Universe' is not so much a 'physics' title, so much as it is a test of your skill at precision timing. The adorable pebbles are being consumed by evil clouds of soot, but in a show of bravery some pebbles are willing to sacrifice their shells in order to defeat them.

They do this by smashing in to each other, creating a shower of tiny rocks that can demolish the one-eyed baddies. Better still, get  he timing just right and you'll hit several monsters. With any luck the remaining eyes, horns and other sundry pieces of pebble will cascade and kill all of them in one go.

This is much easier said than done though as each level is designed as a roller-coaster of loops and ramps designed to delay the rolling pebbles. It's up to you to select when one of the cute creatures can make their journey and getting things just right can range from being elementary to requiring herculean efforts of split-second timing.

Objects in the world including fans can be used to modify the direction or speed of the pebbles, adding further complication to attaining the perfect completion. Furthermore, the 'spread' of the pebbles when they collide can vary significantly enough to ruin an otherwise perfect attempt.

The mix of stringent requirements and random outcomes can suck the joy out of what should be a moment of success as it's not entirely a result of your skill. Thankfully this is all predicated on attempting a perfect completion and the difficulty level flattens out significantly if you merely try to complete the stage by popping the 'royal' cyclops instead.

Pebble Universe's concept is sound and the levels manage to mix up the concept thanks to a variety of pebble types; interactive environments; monster layouts; and the occasional bonus level to distract you. If nothing else it's worth checking out thanks to the change of pace it represents; just expect a spot of frustration here or there.