After playing this game for a while up until I got a rank reset (I don't know why but that's for another day). I have to say it is fun and the game does get harder as you rank up and get better weapons. Sadly after a while it does get boring I mean it's fun playing with people but doing the same thing over and over does lose ones interest. single player is easy to do but story wise is fair at best. Alright suggest you do this make pvp, let people set up modes like iron man or half bullet damg or any game modes that let people pick how they want to play cause 3 modes are not as good as say 10 different modes. Also make classes ex like medic,gunner,sniper,tech then add a class lvling system also add armor to take some damg from high power attacks like that big muscle guy that spams minions. After you do all that then you have the best zombie multiplayer game in town or until someone makes something better.