This game is a bit of an expansion on Children of Brinn, it is a text adventure. Every action you do uses food, if a person acts alone, they use more food, and hence their hunger meter depletes.
This is a zombie themed game. You have to survive 101 days and reach the edge of the city. The meter at the top shows your progress. If you search an area too much, or just have bad luck, your characters will find nothing and move try to move on on their own.
The game autosaves when you are resting at a safe location. That is the best time to quit the game. But quitting any time should be okay, you might just lose some progress.