7 Day SurvivorG 20

This is one of those daunting achievements that feels like a chore to even start. For the 5 Day Survivor achievement you'll need to pretty much play for 10 hours at once, and for this one 14 hours without dying, no saves, and no quitting. Seems a little daunting right? It's not that the gameplay will be difficult for this achievement, it's just that it's long and ungodly boring. By the time you attempt it you'll likely have earned all the other achievements in the game and already played for hours so you'll probably have grown tired of playing it which doesn't help.
I was actually able to unlock 5 and 7 Day Survivor over the course of a few days. I'd play for a few hours, get sick of playing and stop but still able to work towards it without having to start over. What I did was simply put the game on pause and left my Xbox on until it eventually shut down on its own. When I felt like playing again, I turned my console back on, clicked on Dead Rising and was immediately brought to the pressure screen where I left off. I did this several times over the course of a few days for as long as even 24 hours of my console being shut down. This made it a lot easier to complete so I didn't have to play the 14 hours in one sitting. The only unfortunate thing is you will not be able to play any other games while doing so or you'll be shut out of Dead Rising and have to start from the beginning. I don't know if this will work on other platforms but it did work on Xbox One for me. If you want to test it out just to make sure, start a new game press pause immediately, leave your console and let it shut off on its own and come back later and see if you're game is still going.