This is simply the result of a mod - the Far Lands have not existed in vanilla since Beta 1.8 and the fix they made makes it completely impossible for them to ever reappear no matter how far you go out or what Customized settings you use (otherwise, the coordinate scales would determine how far away they start; 2^31 / (684.412 / 4) = 12550824). The version is even shown as "NOLIMITS" after the Optifine version, suggesting they used a mod to remove the 30 million limit as well as the Far Lands fix.
http://minecraft.gamepedia.com/Far_Lands#Cause (because of the modulo by 2^24 (which could even be just 2^8) the noise value can never overflow; 2^24 is the same as 0, as is every other multiple of 2^24; the ultimate limit to how far terrain can generate is 2^31 blocks since the game uses (signed) 32 bit ints for block positions and it will be normal up to that point since doubles have enough accuracy for even 1000+ times that distance. Also, the Wiki makes a bunch of claims that you can go further if you have 64 bit Java but the Java version has no effect at all since ints are always 32 bit and would have to be changed to longs by editing the code; even 32 bit Java can handle 64 bit longs, if more slowly, even for 64 bit, which is why ints are most often used)
Welp, I made it 1,506,001,338 blocks in...
Edit: I did use two mods to do this.
https://www.reddit.com/r/Minecraft/comments/2su65c/i_resurrected_the_far_lands_in_181/
and
M̋͡ủ̯͜c̛͘h ͋ͬd́̏̄i̔̅s̙̯̿tơ̺ͅṙ͉t̾̇͡. ̾V̠̠e̛r̶͕̗y̧ ̡wͩaŗped̫.̶̒͆ ̶W̺ơ̖w̹!
sadly game crashed and then proceeded to kick me back to 29,999,999 blocks on the X-axis
M̋͡ủ̯͜c̛͘h ͋ͬd́̏̄i̔̅s̙̯̿tơ̺ͅṙ͉t̾̇͡. ̾V̠̠e̛r̶͕̗y̧ ̡wͩaŗped̫.̶̒͆ ̶W̺ơ̖w̹!
This is simply the result of a mod - the Far Lands have not existed in vanilla since Beta 1.8 and the fix they made makes it completely impossible for them to ever reappear no matter how far you go out or what Customized settings you use (otherwise, the coordinate scales would determine how far away they start; 2^31 / (684.412 / 4) = 12550824). The version is even shown as "NOLIMITS" after the Optifine version, suggesting they used a mod to remove the 30 million limit as well as the Far Lands fix.
http://minecraft.gamepedia.com/Far_Lands#Cause (because of the modulo by 2^24 (which could even be just 2^8) the noise value can never overflow; 2^24 is the same as 0, as is every other multiple of 2^24; the ultimate limit to how far terrain can generate is 2^31 blocks since the game uses (signed) 32 bit ints for block positions and it will be normal up to that point since doubles have enough accuracy for even 1000+ times that distance. Also, the Wiki makes a bunch of claims that you can go further if you have 64 bit Java but the Java version has no effect at all since ints are always 32 bit and would have to be changed to longs by editing the code; even 32 bit Java can handle 64 bit longs, if more slowly, even for 64 bit, which is why ints are most often used)
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
Yes, I did use two mods for this. I have edited my post to reflect that
M̋͡ủ̯͜c̛͘h ͋ͬd́̏̄i̔̅s̙̯̿tơ̺ͅṙ͉t̾̇͡. ̾V̠̠e̛r̶͕̗y̧ ̡wͩaŗped̫.̶̒͆ ̶W̺ơ̖w̹!