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Hundreds is a game of expanding circles, knotted fingers and daring brinkmanship.
Described bluntly, it's a filling game. When you touch the circles on-screen they turn red and expand and a digit in the centre of each circle increases. When the numbers on screen add up to one hundred, you have passed the stage.
To begin with, Hundreds is about that balance of risk and reward which challenges you to hold your finger on the screen as long as you dare. Every touch of a circle turns it red, and as it grows in size any collision with another object means that it's game over. You'll discover this quickly - the game confidently throws you straight into the game without a tutorial and allows you to make your own mistakes. You are reprimanded on the failscreen with Hundreds' awkwardly poetic slogan 'If they touch when red then you are dead'.
The trick is to seize upon the right moment to touch each circle. Wait for it to float into an emptier area of the screen and you can touch it, lifting your finger from the screen just as some other shape or hazard is about to collide into it. It's a game which tests patience as well as spacial awareness.
It gets more complex quickly, and what's perhaps most impressive about Hundreds is the layer upon layer of strategy introduced as you progress. Greyed out, poppable bubbles interfere with the movement of the circles on screen and circular saws 'pop' your inflated discs down to size zero again. There are also conjoined circles which must be touched simultaneously to boost their size, and the number therein.
The latter is emblematic of Hundreds' flirtation with multi-touch. A pop-up slogan - 'A mouse has one snout but a hand has five' - soon confirms that Semi Secret wants you play with two, three, or four digits poised to strike, rather than one. It might be considered some distant relation of Eliss, though it is a far more thoughtful game than Steph Thirion's frantic multi-tasker.
Hundreds requires an intense, furrowed-brow kind of concentration. New 'feature circles' are introduced and mixed together all the way along its ever-ascending difficulty curve. New play options means new strategies, formulated and adopted as you progress - spacial challenges turn into spacial puzzles. Very, very difficult puzzles.
We've seen filling games on the App Store before, but Hundreds takes that idea and enriches it with ingenious new conceits and clean, effortlessly handsome visual design. Similarly, its barely-there music and effects show the developer's deft lightness of touch where aesthetics are concerned.
Semi Secret Software made its name with Canabalt, the endless running game which sparked a whole genre into life. That game has been imitated and improved upon since, but with Hundreds, it is difficult to see how imitators might pull the same trick. This is the first truly essential videogame of 2013.
Hundreds is £1.99 on the App Store, and is best played on iPad. Download it here.