Sometimes the simplest ideas are the best, particularly when it comes to games. Think of Pac man, Space Invaders, or even Flappy Bird. Blek, from developer kunabi brother, fits seamlessly into this family, even though it's a game that could only exist in the touchscreen era.

A deceptively simple premise - you swipe your finger to create a snake-like line, which the game records and re-draws, with the intention of hitting a number of coloured balls while avoiding the black ones - soon gives way to some fiendishly difficult puzzles. The length, angle, and even the timing of your line all become important, an at times maddening quest to make minute adjustments to your line before helplessly watching it wiggle across the screen, bouncing back and forth (the top and bottom of the screen are, inexplicably, voids into which your line will disappear).

If all of this sounds complicated, in practice it really isn't, and Blek is one of the most intuitive games I've ever played. A mix of trial and error, lateral thinking and, at times, pure luck, is required to solve each challenge, some of which are mind-bogglingly complicated. Closing in on the correct finger stroke takes a bit of patience, but that's more than rewarded by the glow of seeing the targets disappear, one by one. More than once I stumbled on the solution quite by accident, but more often than not, a creative precision is required, a testing your reflexes, foresight, and geometry as you move through the levels - of which there are 60 - and encounter mazes and minefields.

There's a wonderful purity that comes from having no other buttons or controls - all you have is your finger and the screen - and the game play is a triumph of minimalism. It's also a calm, engrossing experience, despite the inherent frustrations your bound to encounter on the more difficult levels; as you become ever more determined to solve each puzzle, minutes can quickly turn into hours.

If there's a criticism to be made, it's that there are one or two spikes in difficultly, levels that appear disproportionately difficult to those which preceded them, and I'm not sure how satisfying the iPhone version will be given the smaller screen, but these are minor quibbles. Blek is, by and large, a sharp, engaging joy where the process of discovery is every bit as rewarding as the moments of jubilation.

Blek is available now for iPad/iPhone/iPod Touch, with the Android version out soon. Head here for more information.