Why are you acting like this is magic and special and we won't have a chance at it again after 30 days? Many, many people have already realized how to use the flood options to recreate the halo and duck hunt game variant.
Because normally you cannot edit some of these settings. You can kinda recreate these things, but these files are "special".
This is a duck hunt where the zombie has the normal human skin and carry a sniper as apposed to the work around people have done where the flood are the ducks and there is one human sniper.