If you do a backup when stop you would be able to start from where the backup was done, say you did a backup at hour 4 and had a power outage at hour 7 you could load your backup and restart at hour 4. When I did my 24 hr races I did a backup at least every 2 hours. Also if you make a second account,if you don't have one,you can play on it if you don't want to do the 24 hour races.