We all know that most of the time, Treyarch makes mistakes for a reason. For this reason I have a small theory on why it is spelt R-E-Z instead of R-E-S.
Who do we know whose name begins R-E-Z? Reznov. My one theory is that as Reznov was part of a majority of major Russain missions in WW2, he was chosen as a soldier during the 'apparent' war of the moon which supposedly took place throughout the 50's.
Now I think that during this war, the Germans attempted to mine the 115 deposits in order to continue their wunder weapon projects, and once again it backfired causing a zombie outbreak. I believe that this is when everyone just went every man for themselves.
This 'could' be why Reznov is at Vorkuta at the start of the 60's. However I do understand that the Black Ops campaign is in no way supposed to be linked to Zombies.
They were my two pence on the subject of Rezurrection. Please reply with your thoughts.
~ Sen_Sim
