Actually... seems like World at War was the big boost to the whole "zombies" deal... way before "left 4 dead" came out, so the others can be thanked for taking the "copy cat" route. I agree that including the zombie mode is Treyarch's thing, plus, combine that with the fact that zombies haven't gotten sickeningly popular in recent years, and it's no brainer that they would bring them back for Black Ops 2. You should also note that they used a lot of the same "zombie laughs" and sounds from the original zombies mode in World at War, so for the CoD series... this is nothing new, and they aren't mimicking anyone else, just keeping up the tradition and sticking with what's popular. Side note... I'm so effing sick of hearing about zombies everywhere I turn... t.v., movies, games, magazines, etc. Give me a break... it's so freakin' played out. I mean yeah it can be fun from time to time but they are really running it into the dirt and if somebody ever were to ask me in real life if I were ready for a "zombie apocalypse" I'd probably slap the dumb out of them... so imo... they fall into the same category as Chuck Norris jokes, the "arrow to the knee" saying, the "r.i.p. ears/headphones" on youtube videos, etc.... started out great... ended up disastrously played out.