My advice is not to buy Sniper Elite: Nazi Zombie Army 2 but to buy Zombie Army Trilogy because it contains Sniper Elite: Nazi Zombie Army and Sniper Elite: Nazi Zombie Army 2 as well as the continuation of the story as if it were called Zombie Army Trilogy Sniper Elite: Nazi Zombie Army 3. In addition to this, you also have the multiplayer where you can still find people to play with next to Sniper Elite: Nazi Zombie Army 2 where you can no longer find people to play with online.
In short, you use the sniper to kill zombies. It's quite interesting and towards the end it gets a little harder. As you are already used to the Sniper Elite franchise, here too you have to find the gold bars and shoot the bottles you find hidden on the map.
Sniper Elite: Nazi Zombie Army 2 continues the story where Sniper Elite: Nazi Zombie Army left off. It can be played co-op with 4 people, so if you have 3 more friends to play this game with then it will be more fun and easier to finish. Enjoy.

What CoD Zombies should have been

Nazi Zombie Army can suck 2