It's one year after the collapse of civilization and self-centered hedge fund manager Joe Wheeler emerges from his specially constructed bunker in search of food. This is a huge open-world Role Playing Game where you have the freedom to play how you want - but your choices have consequences. Your aim is to find other survivors, gain their respect, and build a community. You'll scavenge for supplies, trade, plant crops, go on quests, face moral dilemmas, go to war, and uncover dark, terrible secrets!

Innovative dialog system with characters that remember your actions and form their opinion of you accordingly.
Combines Action-RPG and Real-Time Strategy elements - you can take control of, or issue commands to, any character that joins your community.
Fast zombies and challenging combat that requires you to make use of all resources available to survive!

There's also an upcoming sequel, check it out here!
MATURE CONTENT DESCRIPTION
The developers describe the content like this:

Gameplay features gun violence against zombies and other humans, with some blood and fire effects.
Alcohol and cigarettes are inventory items and can be given as gifts.
In story text, there are occasional references to: homophobia, racism, sexual violence, religion, beheading and torture. Also lots of swearing.