The game has two parts - day at the shelter and night in the city.
During the city you can mend up wounds, talk to the occasional neighbor or trader visiting, construct improvements, stuff like that. During the night you decide who guard the shelter, who sleep etc and take one guy on a scavenging run.
The scavenging run is basically a 2D stealth game where everybody dies really quick from firearms. You can loot ruins, steal from other survivors, try to trade with them or risk stealing/trading with armed thugs/paramilitary/military. There are implicit moral choices. When your shelter is running out of food, do raid children's hospital for some more? Even though you are literally stealing food from the mouths of orphans?
The characters in your shelter react to your choices. Some are okay with doing drastic things, others get horrified and depressed. Likewise, some characters will get totally devastated if they kill someone on a scavenging run, even if that someone was a bandit who was just bragging about robbing a humanitarian aid convoy and raping an aid worker. Other characters will just be "meh" or even happy about bagging bad guys.
This is pretty much all there is to the gameplay. The goal is to survive till the siege of the city is lifted. It is impossible to know when this will happen, though you can listen to news and rumors from radio. Essentially, the length of the crisis is random since hey, war is pretty random.
The game sounds simply but it has surprising depth, like when a bandit you've beaten senseless with a shovel grovels at your feet and begs your mercy, I at least hesitated whether to kill him or not, giving him enough time to grab a pistol and shoot me in the leg. Mauled the bastard, but still. Or raiding the home of an elderly couple for food while they beg for you to stop, but you can't, since otherwise that cute musician girl will starve to death.
So yeah, I recommend the game heartily and I recommend getting people too interested in warfare and war games to play it too. I think I know what I'll be buying to people for Christmas now.
Check the trailers on YouTube, they are pretty powerful on the atmosphere. (Feel free to link 'em here.)