Whilst you were offline, the Ender Dragon got measles and then when trying to kill a sheep who came to the end, he let off a terrible belch, unluckily, an enderman also got caught in the blast. Then, this enderman spread the disease in the overworld.

Trees died, mobs changed, this virus is awful! Even the cake got infected! It is now your job to survive in this terrible place until you get sick of the mouldy cake and the ender torches.