Puzzle games have to walk a pretty high tightrope between easy and difficulty if they're going to succeed as enjoyable pastimes. Take Tetris, for example. Like some stick-thin Russian walking the highwire at the circus, it manages to strike the perfect balance between being easy enough to get into, yet hard enough to provide a stiff challenge.
Some puzzles games don't manage this feat; they wobble about as they get halfway across and then plummet to earth, hopefully to be caught in the safety net of the bargain basement section of your mobile phone network's gaming portal.
Others look as though they're going to topple, the wire trembling beneath their tentative footsteps, then they manage to regain their composure and make it to the other side after all.
PileUp! is one such game.
It starts out being harder than any other puzzle game we've come across, and doesn't let up. Following the tried-and-tested mechanic of Tetris, whereby pieces drop slowly down the screen before collecting at the bottom, it looks easier than it plays.
Clusters of three coloured balls replace the angular bricks of the timeworn classic – though you can rotate and move them around – and it's up to you to get four or more similar-coloured balls in a line at the bottom of the screen, Connect-4 style. So far, so steady.
Where the wobbles begin is when you try and match the colours that are falling with the colours already at the bottom of the screen.
Blue, red, orange, yellow, purple and green are all used, and early on, too – you're not given any grace. That's before shades of the aforementioned colours start appearing, too, making things even more difficult. If you can't tell your puce from your lilac, you're in trouble.
As a result, discerning what colours are awaiting the dropping trio of balls, and what pattern they're in, is a very demanding task. It'll take the first five levels or so until you become mildly comfortable with the idea; until you do it's a fevered rush as you hope to not put a foot wrong and come tumbling off yourself.
But as you progress further, you'll find yourself making better decisions – it's often about snap judgements in PileUp! – and actually starting to enjoy yourself. It's at this point that you'll realise just how good a puzzle game this really is.
Each level has a certain objective that you need to complete and it's always different; variety truly is the spice of life. Some levels require you to do little else than clear the screen; others insist that you reach a certain points level; others still demand that you do one or the other before the strict time limit runs out, which is often as short as 30 seconds.
It's the latter type of level that makes you sit up and realise that PileUp! isn't as shaky as you first thought. That it was, in fact, playing to the crowd, adding a soupcon of danger to proceedings.
The first level that makes you appreciate this does so because (and you don't realise this at the time) the huge pile of balls at the bottom of the screen is ordered in a pattern; when you place the dropping cluster, whatever way around, you end up setting off a chain reaction that clears around three quarters of all the balls.
It's a great moment and turns around a game that, up until that point, is a bit uncertain – it doesn't promise greatness, but nor does it turn you off altogether. But that one moment in that one level just shows you a glimpse of what PileUp! is all about and what it can do.
And it's all you'll need to want to stay for the entire show. You'll be glad you did, too. Bravo, indeed.