A bit of everything over time, from new cities to bugfixes; some times in big chunks with delay, sometimes small and more frequent. Game builds up on survival, but on multiplayer people themselves add lots of intrigue. It has RPG system. The world is huge.
For example, I was once as fresh character invited into small party to survive together. It went well for half an hour, until invitors realized I am no longer useful for chopping wood and decided to chop me instead. I managed to run away with heavy wounds, but patched myself, then found a pistol with few bullets - noise of which I used to attract a horde of zombies into their fort as a revenge.
If you are into singleplayer I think there was also NPC mod somewhere, you gotta check it up if lonely survival isn't option for you. I am not sorry for purchasing it even slightly, but Steam version has more advantage, as you can play both on Steam and non-steam(gog) servers, where gog(non-steam) allows to connect to non-steam only.
