...no? I've never heard this before. There's certainly nothing in game which resembles one. It's quite possible that people have made up their own storylines and what not, but there's not one built into it.
oh,but there is! Go check the Achievements list!The final place to go to is called THE END! you have to fight an EnderDragon there and the game is finished!But it still is a sandbox game.
Minecraft is awesome. But creepers...they suck. I was building my famous gold mansion, then creepers came and blew it up! My pool, my safe, my kitchen, and my safehouse was destroyed! But I like spiders. They are cool.
Hate creepers? Post on my profile! I might be able to help.
Harder to die? You have to try to die in that mode! xD
The first night isn't difficult because the first night usually does not include a "that's a nice finely-assorted and decorated kitchen you have there. What say you, brothers?" encounter. Granted, I could have stopped being lazy and just add an axepickin' door, but still. Nice things. It's not your life, it's the life of your creations. That's what hurts the most in Minecraft ;_;
....which all leads up to how peaceful mode makes the game drab. Somehow.