Pretty creative...
I just don't understand - is the lightning striking always at the same place? What means the "off by x meters" info then? Cos it show different numbers although I quickly click at the same place several times.
The lightning strikes the same place until you give your guess. At which point the position is randomized for your next guess.
So if you click several times you'll be trying to guess where a lightning that hasn't struck yet will be.
The "off by x meters" is how close you got to the lightnings actual position.