Alternate World
Angel Nebula50
Difficulty Below Beginner
Terrain Aerogel, but looks like Outer Space
Entrances 1
Exits 1
Water? No, but the whole track is aerogel!

Alternate World is a spiral-like track even easier than Beginner! It can't be normally unlocked and can only be played if you raise the Black Void Shooter's mood to 100% during The Melancholy of Black Void Shooter. See the picture for the entrance and exit of this track. Also, the whole track is actually made of Aerogel, not Outer Space!