Instead of the same game x3 why not add in some red dead undead nightmare, and resident evil, and a hint of left for dead. I wonder why no one ever made a mmo about killing zombies? Like a left for dead, on dead island type game that there are tons of people trying to surive unstoppable hordes of zombies.
Combining the 4 CoD's would be no different.. it will just be the next game basically.. and for Dead Island, Black Ops and WAW both have zombies so once again they are nothing we haven't seen. Joey is right it's called Nazi Zombies.