Don't Dig Up

Seed Varients (case-insensitive):

This seed, also known as the "Remix Seed", flips the usual order of player progression through biomes by having the player spawn in the central part of the Underworld. Above that are, in order, a Glowing Mushroom biome, an underground version of the Surface biomes, the Underground layer, the Cavern Layer, and then the true surface which is the Evil biome, without a sun.

A flat Ash Block "island" is generated in the central part of the Underworld, with Ash Trees growing and lava not spawning at all. Mimics now spawn in pre-Hardmode, but drop Gold Chest loot during this period instead. Plus, slimes have a chance to contain Fallen Stars as their bonus drop, and they can also spawn from broken Pots (such ones will always contain a Fallen Star). In addition, Lava slimes do not generate lava upon death in Expert Mode and above.

The Tax Collector replaces the Guide as the starting NPC.

While generating

 * The Terraria logo rotates and flips upside down.
 * The background turns into the starry sky background of Space.
 * The Corruption music will be played, regardless of world evil.

World icons
The world icon of a Don't dig up world is an Ash Tree.