7 Days to Die is a unique open-world zombie game that combines elements of survival horror, first person shooter, role playing, tower defense, mining/crafting, scavenging and exploring. The developers say:
“7 Days to Die thrusts players into the aftermath of the fall of civilization with only their wits and bare hands to survive. In this continually evolving title currently in alpha stage development, players must explore the open world alone or with friends to build tools, weapons and shelter against the dangers of the reanimated dead, infected wildlife and the world itself.”
7 Days to Die was released via Early Access on Steam for Microsoft Windows and OS X. As of June 2017, the game scored a “very positive” review on Steam despite still being in alpha stage development. The PlayStation 4 and Xbox One versions were released in June 2016 through Telltale Publishing.
The game takes place in the fictional county of Navezgane, Arizona. When you start the game, your player spawns into a random part of the map. It might be the desert, the forest, a burned-out forest, or snow. You must find clothing, shelter, food, water, and other supplies while fending off zombies.
7 Days to Die features a stealth and distraction system to avoid unnecessary conflict with the zombies. Carrying raw meat or other foods that smell means the zombies can find you. The zombies can climb, dig, swim, destroy walls, and break down doors. You will need to set up traps to defend your base in order to survive.
This game is like Minecraft with its mining/crafting elements, but with better graphics. You have the ability to craft, destroy, and manipulate objects in a physics-simulated environment. 
There is no real objective except surviving as long as possible. As the days go by, the zombies get tougher and more aggressive. This Early Access game is not complete and may or may not change further. The developers have hinted at a possible storyline to be added in future updates.