As much as I try to stop myself from abusing that in roguelike games, I often can't.
If I press Alt+F4 during battle that is going wrong way, I can return to the latest autosave sometime before the battle.
This is rather normal and while I do encourage devs to fix this (by reading Alt+F4 command and giving "are you sure you want to quite the game?" prompt), I do not expect them to.
However, there are some bugs associated with abruptly closing the game (which probably includes crashes or PC power off, etc.)

When I Alt+F4 while choosing a reward, I ended up without any reward (deserved, dirty me!)
When I Alt+F4 after leveling a character or using a skillbook, I loaded back before doing that (abusable, please fix!)
When I Alt+F4 during battle with second boss at Blood mist 4, I loaded with rewards from first boss and the second boss nowhere to find! (abusable and sad. Please fix!)