A few days ago Notch put up on a fascinating post up on his blog discussing the nature of fear. Within said article he began talking about how he has injected fear into the gameplay of Minecraft, and ended up talking about a new mob that will be haunting our nightmares with the release of the Adventure Update. Dubbed the Endermen, these lovelies just want to be left alone, away from prying eyes. Much like any other Minecraft player, they just want to move their blocks around in peace. The truly creepy factor? They won't attack until you look at them directly and then look away. Much like some other horrible nasties I can think of, they will teleport to your location and attack.
I have a couple of conflicting reactions to this news. On the one hand, from a game design perspective, it's always important to continually change up the game (no pun intended) on your player base. Providing new content the way the Adventure Update is, it's a perfect time to add a new monster to the Minecraft pantheon. Up until this point there were no monsters that could feasibly alter what you've created -- unless, you know, you let your guard down and things exploded around you. Now not only do you have to deal with the consequences of your actions (only you can put your reticle over the Endermen, drawing their attention your way) you may now have to deal with monsters moving your blocks around.
So my second reaction? Terror, complete and absolute. I feel at this point that I have no mechanisms with which to protect my structures from the threat of disassembly -- and that's not creepy, that's horrifying for someone who just wants to build.