The things that really separate DayZ from other games are
-Zombies. At a minimum, they are an annoyance. But at worst, they act as signal beacons to other players. You see them in a town from far away, that means a player is in there. You might see then chasing other players running through town. Or when a shot goes off, you'll see them run in the direction of the person who shot. (Currently this is very limited at best in Standalone.)
-The moral dilemmas you face when you run into other players. Do you help them if they need it? Team up with them? Ignore them? Murder them outright? Rob them and send them into the woods with nothing? Play nice and betray them later?
-The tactics involved in standoffs or outright firefights with hostile players. There are lots of wooded areas and buildings to use for cover. Coordinating maneuvers with teammates, whether they're near or far. Sometimes these can last hours because you don't want to make the wrong move and get killed.
Things can get very tense in this game. Something I've only felt in competitive matches with others. The feeling of potentially dying, losing all your gear and having to start from scratch heightens that.