Superflat



Superflat (sometimes called Flatlands) is a world type replacing the normal varied terrain of the Overworld with customizable layers.

On a classic superflat world, the terrain consists of one layer of bedrock, two layers of dirt, and one layer of grass; the surface of the world is completely flat and at height y = 4, with the exception of NPC villages and terrain features, if they are enabled. Since the height limit (256) is unchanged, there is then slightly less than one-third more vertical height available to build above-ground structures as compared to a normal world. Mobs spawn as normal, including Slimes; however, there is no "Void Fog" as would ordinarily be caused by being close to the bottom, even for areas that are completely shielded from sunlight, whether in Survival or Creative mode.

Because of there being chests in villages, and villages frequently spawning near the spawn point, it is possible to use Superflat as a survival challenge map. However, the high amount of slimes makes this extremely difficult to an inexperienced player, if playing on any other than peaceful difficulty.

The Nether and the End both generate normally (except in the console edition where the nether is flat). In order to create a Superflat world in SMP, the level-type flag in server.properties must be "FLAT", instead of "DEFAULT".

In SMP, once a world is created, the server.properties fields have no effect on chunk generation. Instead, just like in SSP, the level.dat fields for "generatorName", "generatorVersion", and "generatorOptions" are used instead. If you want to alter a world after initial creation, these are settings to change.

Customization
Upon selecting "Superflat" in the World Type box, a new button appears underneath labeled "Customize". The customize menu starts out with the "Classic Flat" preset of one layer of grass, two dirt layers, and then bedrock underneath. There are two buttons available to customize Superflats, which include the "Remove Layer" button, used for removing unwanted types of layers, and the "Presets" button, used for selecting any of eight currently available presets. If you can understand the preset code syntax you can still create presets of your own by entering the correct block IDs into the 'preset code box', where these changes can be previewed and applied. (Direct Customization is not available.) In addition, superflat worlds can have certain terrain features, besides villages, such as long grass, lakes, and strongholds, which can additionally be customized using the same code box for block layers. These changes also made tweaks to previous world codes, to include the new generation features.

Presets
Presets are shareable. As a preset is selected, a box on top of the screen has a code you are able to highlight and copy. Similar to how new worlds are shared through seeds, presets can be entered into this box to recreate someone else's preset.

Preset code format
At a future point there is expected to be some way of choosing block types merely by selecting them from a menu. For now, you must type in a correctly-formatted preset code.

The code is a string of numbers, semicolons, colons, commas, and lowercase "x"s. Each code has four main parts, divided by semicolons. These are:
 * a version number (used to allow preset codes to be shared even if the code format changes),
 * a list of one or more block IDs,
 * a biome ID
 * a list of structure generation options (may be completely empty)

The block list is a comma-separated list of block IDs, ordered from layer 0 up; if the entry for a given block has an "x", the number before the "x" is the number of layers to be generated, and the number after is the block ID. A block ID can be followed by a colon to specify a damage value.

Structure generation options (described below) may have additional parameters, for example "village(size=0 distance=9)".

Preset code example
Consider the preset code

It consists of the following elements:
 * — version number.
 * — comma-separated list of block IDs.
 * — one layer of Mossy Cobblestone on layer 0.
 * — 250 layers of air, from layer 1 to layer 250.
 * — one layer of obsidian, on layer 251.
 * — one layer of thicker-than-usual snow, on layer 252.
 * — biome ID, in this case Extreme Hills.
 * — a comma-separated list of structures.
 * — this will populate the world with seven strongholds at the default distance and spread. In this preset, these will appear in mid-air.
 * — since Extreme Hills is an invalid biome for villages, this will do nothing.
 * — biome-specific decoration.
 * — activates dungeons.
 * — activates mineshafts at the default placement frequency. These will appear in mid-air as the preset contains 250 layers of air.

A block can also be repeated over multiple layers simply by repeating the block's ID, e.g.  would give the same result as.

The Player will spawn on the topmost solid layer, and will spawn under water or lava if there are layers of those above the topmost solid layer.

Note that there are several criteria that must be satisfied before some features can appear: For example, to have an 'End' superflat world with obsidian pillars, the biome number must be 9, the superflat string must contain 'decoration', and the top surface block must be End Stone. In this particular case 'Structures' does not need to be turned on in the world options.
 * The biome number must be correct. For example, at present villages can only appear in biome numbers 1, 2, and 35, plains, desert, and savanna.
 * The correct structure code ('village', 'dungeon' etc.) must be present in the superflat string.
 * Structures must be turned on in the world settings. (This does not affect 'natural' objects such as trees, flowers, mushrooms, giant mushrooms. Obsidian pillars in the End also count as 'natural'.)
 * There must be suitable terrain for the structure to appear on or in. This applies to most features except for mineshafts and strongholds. Villages are a partial exception; they will not form in mid-air, but will form provided there is at least one solid block layer. If there is only 1 solid layer where they form the gravel roads will fall, trapping indoor villagers (unless it's a desert village since they have sandstone roads).

Attempting to use an incorrectly formatted preset code causes the game to default to the Classic preset.

Using almost any of the technical blocks will crash the game as they do not have item forms at all (which the preview needs).

Resources that can be found in a classic Superflat world
The resources below can always be found, regardless of the "Generate Structures" option.

The resources below can only be found if the "Generate Structures" option is enabled. These do not include trading with villagers.

Village chests may contain these items:

Sandwich spawn
When making a flatland world, your spawn is never the same. The spawn is a 20x20 cube, despite your initial spawn.

Disregarding the last post the average spawn is calculated.

History
SPONGE BLOCK BECOMES SANDWICH!

Trivia

 * The wiki editors are too lazy to do trivia today :(