For its age its a good top/down zombie shooter buy it on sale
Nation Red is a really amazing zombie shooter game in third person perspective.

Pros:
+ nice design, different maps / locations
+ playable in singleplayer, coop, multiplayer
+ different modes (e. g. defending a barricade, survival, king oft he hill, free play)
+ convenient music, good sound
+ different survivors with special abilities
+ all options possible (graphic, audio and so on)
+ selectable level of difficulty
+ you can turn friendly fire on/off, collect exp together or alone
+ a ton of zombies and massive growing waves
+ many different weapons which you get by killing the zombies
+ health kits, short-term skills (also by killing zombies)
+ levelsystem (you can choose an ability with every new level)
+ players can resurrect teammates at any time
+ 140 achievements to hunt, leaderboards
+ IT MAKES FUN!

Cons:
- no story (in Singleplayer you have missions, but no profound story)

This game is for people who really enjoy using many different weapons, having action all the time, killing non stop zombies without thinking much and without a break.