That totally makes sense! The music is great too, it's a nice touch.
My gut tells me maybe 1 pt per hour, instead of 1 pt per day; you could still display which day was reached at the endslate (i.e. "You survived to day 3! Score: 70")
Rebuilding your flock is interesting. Perhaps +1 sheep returned, up to a max, as a reward when each day/night cycle is completed?