What initially sounds like a variation of long running (and fairly worn out by this point) internet meme is something that's actually real. Accomplished Minecraft modder Hans Lemurson has created a version of Minecraft within Minecraft.

Made entirely out of Redstone, it's not exactly a carbon copy. Lemurson's creation is essentially a very rudimentary platformer that allows for basic environmental manipulation. But if that doesn't describe the very essence of Minecraft, I don't know what does.

True it's also somewhat cumbersome; there's a switch that toggles between movement and block removal/placement. Not to mention extremely slow; there's a five second delay between button press and ensuing action. Yet given the limitation of in the game's tools, it's supremely impressive nonetheless.