There's a place in Minecraft called the Far Lands. It's the point where the game's code, which builds each world procedurally, starts to collapse under the weight of its own sums, breaks apart and glitches out.
The New Yorker has a great interview with Kurt J. Mac, a man who is trying to walk to this point, the end of Minecraft's world. He started his quest in March 2011, and is still going.
The sad/amazing part is that we know how far away the Far Lands are, at least in Kurt's build of the game (newer versions of the game have had the "feature" removed). From the point at which you start your game, they're 12,000km away. In his three years of walking, Kurt has travelled 700km. He's...got some walking ahead of him.
He'll never get there, but that's not the point. The point is the journey, which he's documenting on YouTube (and raising money for charity with!) as a sort of wandering podcast, each one not just a story of his travels, but an example of the crazy stories that can come out of playing Minecraft.
A JOURNEY TO THE END OF THE WORLD (OF MINECRAFT) [New Yorker]