Note: This involves messing around with game files. Make a backup of your files in case something goes wrong.

First of all, you want to create a new world. You may choose any name for it, as long as you can remember it. Don't enter the world. Instead, you close the game.

Next, Find your AppData files. From there, look for the game's files.

(Optional) Backup the game files if you want to be safe.

In the game's files, look for [World Name]_main and [World Name]_tiles. If you want to create a corrupted world, delete those 2 files, and re-open the game. If you open this world, there will be no blocks. You immediately beat the game.

However, if you are looking to create a world with the seed 69, (You can't just type in 69 in the seed box in-game, as doing so will crash the game) Open your [World Name]_main file, and scroll down a bit until you find seed="[Your Seed Number]". Change the seed value to 69, save it, then re-open the game.

The corrupted world could be used for a quicker subcategory for Void% (If that will ever be a thing) where you create a corrupted world, then open the world and beat it immediately.

The seed 69 world could be used for a different subcategory of Nice% where you create a world with the seed 69 and beat it as fast as possible.

Credits to BeLegasy for finding this glitch.

(btw note from belegasy, u can create a world with 69 seed by typing 069 in world seed generation, without going into game files)