GridBlock

Before we had such things as iPhones and iPads, portable entertainment was a little more rudimentary.

A particular favourite with children of the '70s and '80s was the classic ball-bearing puzzle, where you'd have to get all of the small metal spheres into a series of holes. It was simple but devastatingly effective at eliminating boredom on those long trips to visit elderly relatives.

In a strange twist of fate, we appear to have come full circle with GridBlock. While it's an iOS puzzle title, and consequently runs on the kind of high-tech wizardry that we could only dream of back in the '80s, it actually shares a lot of similarities with those old ball-bearing conundrums.

Using your device's accelerometer, you must guide a series of coloured blocks onto similarly coloured grid tiles. Blocks often have more than one colour on them, and a quick tap on the screen will rotate all of the blocks on the screen, revealing another colour.

The concept is simple enough to grasp, but it soon becomes much trickier than anything you might recall from your youth. Later in the game you'll need to prioritise your blocks in order to avoid having to totally restart the level because you've run out of the correct colours.

There are also medals to collect on each stage, some of which call for forward-thinking on your part. For example, one level has medals stuck behind a red grid tile, which means you have to use a different colour in order to cross the tile and grab them.

Despite some rather rough visuals and the requirement that you play the game bolt upright (slouchers need not apply here - the lack of accelerometer calibration means you need to exhibit outstanding posture throughout), GridBlock plays like a dream.

The initial download is free, but to experience all of the levels you'll need to spend cash. This is freemium done right, though - you get to sample the game for nothing before deciding whether to commit your money.

Fans of handheld puzzle titles are advised to at least give this a spin. You'll have lost nothing because the first two chapters of the game are free.

After that, we suspect that the unique gameplay - punctuated by a subtle hint of ball-bearing nostalgia - will be enough to ensure that you stay for the duration.