The best games are often the simplest, but rarely the cheapest. Big Top 10 hits the target in both cases, offering unbeatable value for the number-obsessed iPhone and iPod touch gamer.
All you have to do is drag your finger over a 5x5 grid of single digit numbers to make a sum of 10. The line must be continuous and diagonals aren't allowed.
Sounds easy, right? And much of the attraction of this 99c/59p game is that almost anyone can play it.
Of course, its addictive nature quickly comes into play, too because as you make longer and longer chains, the more points you're awarded.
Short sums such as '9+1' or' 8+2' are always good to dash off quickly to remove those big, unwieldy numbers, allowing you to trace longer chains. For example '2+1+4+3'.
But the real twist comes in the limit of 59 seconds you're initially allowed. You see, as well as points your sums will gain you extra time. You can even push the counter back over the minute mark when you get good.
In addition, as you get in deeper, you'll start dealing with a full range of numbers from -9 to +9, incidentally including 0. The negative numbers really begin to stretch your mental arithmetic in a way even the likes of the Brain Age (Brain Training in Europe) don't.
And there's more.
Power-ups appear. These don't have any numerical value but modify score, time or the numbers on the grid if included in a chain. For example, there's the clock which will halt time for five seconds. If you can get the bomb into a combo, it will explode and those numbers around it will be added to you score. The 'x2' multiple will double any score you make for the next five seconds, while the star reduces all the numbers on the grid, making it easier to make longer chains.
More generally, you can also shake your iPhone or iPod touch at any time to get a completely new deck: the cost is those seconds you waste in the process.
So Big Top 10 has a elegant concept, but what makes it stand out is the quality of the presentation. As the title suggests, the theme is circus - Big Top, gettit? - so you have brassy oompha music, stencil graphics and a slightly off-kilter atmosphere.
Actually, the combination of the music and the sound effects really sets off the gameplay as when you get, say, a three number chain, the word 'fair' will be splashed up together with a burp tuba. Get a longer chain and power-up though and you might be rewarded with a 'Smashing' and a tootle of some other instrumentation.
When the action's really frantic, the soundtrack becomes almost procedural in terms of the sounds your chains create. There's the warning tick-tock when you're down to your last ten seconds to raise the panic too.
Completing the features are the options to email the challenge of your top score to you friends via your default email client, and play a head-2-head Versus mode of the game with someone on the same wi-fi network.
It all adds up to one of the most immediate experiences we’ve had on the iPhone. Highly recommended for anyone with the slightly interest in numbers, and value for money.