This is a setup world with the Master Hardcore Gamemode-In-A-Box preset and ready to be started.

Read more about the device itself here: http://www.planetminecraft.com/project/gamemode-master-hardcore-mode-v1/

The mode adds three new rules:

1. It's always night after the first bit of day (you have an option to play a full day).
   
   
   
2. Animals don't give you food (so farming is important).
   
   
   
3. You can't craft chests (though Ender chests and naturally spawned chests are ok to use).
   
   
   

The box enforces all these rules for you and also turns Ultra Hardcore on by default (you have an option on the back to turn that off too).

Requires the newer 1.8 snapshots (for the updated clear command).

This is the same world I'm using in my Let's Play (the video above which introduces the gamemode as well).

Just save the zipped world directory to your Minecraft directory and you should be good to go after hitting the start button on the cube.  It's not impossible to get started without giving yourself the full day, but the full day certainly helps the first time.

Enjoy!