Rechner Calculator - when good gestures go bad

How do you know if your touchscreen app is too reliant on obscure gestures? The answer is quite simple:

  1. When they are the only way to trigger key functions
  2. When the effort required to memorise the gestures outweighs any efficiency gains they could ever provide

And in the case of the Rechner Calculator - when the gesture guide is itself almost impossible to fathom...

Rechner Calculator.png

Admittedly, there is some logic to connect the gestures to the actions but it's not a natural mapping - after all, it's the physical component of a good gesture (pulling a photo or map wider to zoom in) that makes it enjoyable and satisfying to use.