Apocalyptic World
Are you finding Minecraft too easy? Force your world into darkness and rise the dead!
Features:
Apocalyptic World adds many features including zombie brutes, large and powerful zombies with muscular bodies, increased spawns for undead mobs (currently zombies and skeletons), unique types of zombie and skeletons that spawn such as zombies with swords, marauder zombies (with two iron axes and an iron helmet), miner zombies and even assassin zombies with enchanted armour (most armour from these mobs have a chance to drop and some have attributes/modifiers).

