Light, the game will be reopened as soon as there's been a successful rollback - ticks will start 24 hours as of the successful rollback tick.
I.e. if last safe backup point was at a 5pm tick (with the backup occuring at 17:30), the game will reopen as soon as a rollback has been completed, and ticks will start at 6pm the following day.
Also:
Many many thumbs up, PATeam.
<3 u Richard!!
edit: Richard got there first