So recently I got hit with the vault sav bug. Apparently it is caused when your phones's memory runs low or the battery dies whilst having the app open. What it does is currupt your vault's save data setting it to 0kb and makes it so that the app crashes on the loading screen. It is pretty frustrating to lose so much progress and after having started up a seemingly successful vault after two other failed attempts... Anyway, it seems there is no real way to recover save files unless you manually back them up. So while I rather enjoy the Fallout Shelter I would recommend being careful. 1. Make sure you have a good amount of room on your phone. I have not seen a recommendation on what to allocate but mine bugged out at 0.88gb remaing space. 2. Make sure your battery is adequately charged. If left on for an extended period of time keep it plugged in. 3. Make backups of your vault's save data. This can be found along the path of storage/android/data/com.bethsoft.falloutshelter/vault#.sav 4. I would not recommend buying lunchboxes or Mr. Handy's untill the bug is fixed. If you are unfortunate enough to get the bug and the app gets stuck on crashing on the loding screen, deleting the currupted save file should fix the issue (albeit temporarily). I like the app but I think I am going to wait for an update.