I've just spent the last half hour messing about with the Cadence demo. It's a musical puzzler in which you draw lines to connect points that, through what becomes a fairly convoluted process, creates a loop of unbroken music. For instance, it'd be difficult to explain why exactly the above diagram works—except to say the squares reflect beats, the right-hand circle stores them, and that, over the course of the levels up to that point, I'd managed to learn enough of the game's rules to sort of intuit the answer.
It's an entertaining time-passer, and one that's currently seeking Kickstarter funds. The campaign is asking for £25,000, although with 8 days left it's a long way off that total.