In any media, expanding a simple, tightly honed experience into ambitious new territories is a risky business.

Think of cinema: both the Matrix and Pirates of the Caribbean trilogies got it wrong, adding a whole heap of new stuff to the sequels while forgetting what made the originals such fun.

Conversely, the reason The Empire Strikes Back is regarded by many as the definitive Star Wars episode is because it took what was successful about the original and chose very carefully where to expand and evolve.

Enigmo 2 takes an ambitious step forward from the award-winning original, staying faithful to the spirit and style of the original in the transition to 3D.

The goal remains to direct a stream of water droplets (though they act more like ball bearings) into a receptacle, which is usually located in a fairly awkward position at the opposite end of the level. You do this by sliding a preset inventory of objects into the level, aligning them so that the droplets ricochet in the desired direction.

These objects vary in bounciness, with some effectively sending the droplets hurtling off in a new direction while others take the pace out of them and filter them through like a funnel. Each can be angled by touching a surrounding indicator and dragging in the desired direction.

In addition to water droplets, Enigmo 2 introduces lasers and plasma particles. Lasers, as you might expect, can be diverted through the use of mirrors, while plasma particles require the careful positioning of mini-black holes, the gravitational pull of which alters the particles’ trajectory.

Levels grow to feature combinations of the three elements, with one being used to activate a vital switch for another. This clever interplay and the consistently inventive physics-based puzzle-solving remain as compelling as they were in the original.

So, Enigmo 2 hasn’t forgotten its roots, but what of the brave step into the third dimension?

It’s a qualified success. Having to consider more than is immediately apparent when approaching a level is a definite step up in the scope and challenge of the puzzles. It really gets your mind working in a different way, and as such makes Enigmo 2 the worthwhile sequel.

The trouble is, in adding this extra layer of complexity, Pangea risks alienating the legions of casual iPhone owners new to the series, or even those who only dabbled with the intuitive original. The 3D controls take some getting used to, and you never grow entirely comfortable with having to constantly rotate the puzzles to try and get a proper view of proceedings.

The 3D manipulation itself is achieved via a double-fingered drag of the screen (a single-fingered drag scrolls), with objects rotatable in any direction depending on how you’re looking at them.

The trouble is, while the graphics are excellent they’re not quite able to convey a proper sense of depth: background elements often blend confusingly with the foreground. Perhaps an exaggerated change in the colouring of foreground elements would help.

Still, if you’re patient and committed enough you will get a grip on the controls. Being able to tap a part of the level to automatically align an object to it is an excellent design decision which, when mastered, eases things considerably.

If you’re a veteran of the first game, you’re likely the type of patient, capable person who'll take to the sequel the easiest. To you, I would say that you can add an extra mark to the score below - you’ll find Enigmo 2 to be one of the most spell-binding puzzlers on the App Store.

To everyone else, I'd recommend the first game as a far better entry point to the series. Once you have the gist of that, prepare to have your mind blown by this ambitious sequel.