How about a new gamemode called infected?
Everyone gets the same gun.
There's 1 person on one team, that's the infected and the other people are in the other team.
That one person has a melee weapon. Their objective is to kill everyone on the other team. If the infected kill a person on the other team, the person he killed will join the infected. Like the one in Mw3.
I don't understand why people don't want a zombie mode. o.o Like a survival. And customizable attachments would be awesome, but not necessary. This game doesn't need it, it's just in my opinion. Anyone else agree?