This nazi zombie map does require 2 mods:

-Modloader 1.4.5 Link: http://www.minecraftmine.org/minecraft-1-0-0-modloader-1-0-0-mod/

-Feroullos gun mod 1.4.5 Link: http://www.planetminecraft.com/mod/145-ferullos-guns-mod/

They are really easy to install. you will also need and archiving system. Link to 7-zip

below. the archiving system is just to open up your minecraft.jar (A.K.A minecraft) and its under the bin folder.

Link for 7-zip: http://download.cnet.com/7-Zip/3000-2250_4-10045185.html

REMEMBER to install modloader first. This map does not work on multiplayer becuase the mod will crash your minecraft only in used on multiplayer. It works just fine on singleplayer. L.A.N servers are considered multiplayer so don't use this mod on a L.A.N either. Play on easy or harder.