Seems like the developers at 11 Bit Studios are onto a winner. Their latest release is a survival sim game called This War of Mine which takes place within a war-torn landscape of a ruined city and calls for you to scavenge, defend your bases, and generally take care of your little pocket of survivors until the 'end of the war' and the end of the game.
The game was released on November 14th and has been floating around the Steam Top Sellers list since then, having made back its development costs in just two days. That's the mark of a popular game.

There was a patch released to the public today, and with it the news of the recouped costs as well as a few other bits of information like the percentage of players who made it to see the end of the war (less than 11% in case you were curious.) If this has made you curious about the game it's currently 10% off on Steam right now.
Patch notes are as follows:
Features and tweaks:
- A new radio station, featuring the music by Cool Kids of Death.
- Unlocked two additional dweller setups on higher playthroughs.
- Graphical improvements on various locations.
- Minor changes in French, German and English localizations.
- Minor animation improvements.
Fixes and balancing:
- Fixed "Input Not Supported" bug on Windows.
- Changed fullscreen mode handling on Windows.
- Improved game stability based on crashdumps sent by players.
- "Aggro bug" fix. NPCs should no longer attack or flee without reason.
- Fixed broken trade. NPCs should no longer trade their entire stock for one item (Marketplace, Garage).
- Price changes now have an impact also on selling items to NPCs.
- Fixed an exploit that allowed players to prevent items from getting stolen during night attacks.
- Fixed a bug with getting stuck with only one initial dweller group.
- Fixed a bug with incorrect shelter description when Reinforced Door was built.
- Fixed a bug with visible gendertag in shelter description.
- All achievements can now be unlocked.