I have created a single command block creation, heat death!
Do you think Minecraft survival is too easy? If so, you might be interested in this challenge I've made, using no mods whatsoever.
Essentially, this long command runs and creates an array of even more command blocks. These command blocks in the world are responsible for creating the fire around you. The fire that you see falls from the sky, the same applies for the lava to mimic that the sun has reached extreme temperatures. This fire won't stop from coming, and sooner or later, it will burn the resources from the surface. You would be forced to live underground temporarily, and then resurface when you are equipped with fire resistance for whatever reason. Also, it's always day time/night time (whenever you execute the command)!
The way this works is based on a single entity, the minecart spawner. A minecart spawner will always be summoned above you, spawning in small fireballs in a certain distance within a radius from you. It is then killed, and the only way to see this minecart spawner is if you reach Y: 255. The mechanism also spawns in falling lava, which is then converted into flat lava that does not despawn. If you wish to turn off the machine, you can do so by destroying the bottommost command blocks.
NOTE: This mechanism will only work in the 1.8 snapshots and up.
If you want a faster rate of destruction, run the command more times!
Do you accept the challenge?
All you have to do is create a new world with cheats on, go into creative mode, place the command block, copy and paste the command, and then initiate it.