Single window application that will show up a 4 days reverse timer and a curved line that will show up progress with vertical line and a label (see attached).
The showed progress will be paired to an apple watch heart beat monitor.
That's how it should work:
Day 1/: The player will physically climb on a real bicycle and start cycling, wearing an Apple watch.
The system should detect the beat rate and start filling up the progress line.
It should never fill up more than a 25% of the entire line (= 1 day).
Day 2/: no matter what happen the day before, the line should be at its full 25%
... and so on and so forth until filling up the 100% on end of last day.