File:Shadowlands tile.png

Shadowlands explained

 * The real level (shown as a shaded rectangle, bottom right section) is where all the walls, lights and creatures are; you start at the bottom where some lighter circles are, and make your way through the level to the north/top, where you can see a brighter "WM slide" section and a round lit Tower area.
 * Investigation-SMALL-75x43.gif you go out of bounds, hit a certain trigger (UG level only, under investigation, see below) and walk far enough to the west, you'll eventually reach the brighter area which has shadows on it. That's shadowlands. The surface is flat but has shadows of windows, pipes and other elements as well as light circles similar to the ones found at the beginning of the real level.
 * That's because the texture (or image) that contains all the shadows for the level is only large enough to cover the "real level" which includes in-bounds areas and OOB up until unstable grounds. So once you step onto unstable grounds on the west side of OOB the shadows wrap around like a repeating wallpaper. This is illustrated by a magenta rectangle to the left of the real level.
 * For example, the bottom/middle side of Shadowlands that you reach after walking west for a long time has the same shadows and light circles as the beginning of real UG level because you're exactly one width of the level further to the west now.

Regarding triggers

 * In the PD video, no additional triggers were activated beyond what was necessary to glitch out of bounds, and Shadowlands were still visible.
 * In UG, according to this video by a renowned Journey streamer Tara: https://www.youtube.com/watch?v=jBcCVwVo95g, "the shadowlands are visible before the history lesson if you have gone through the entire level normally. They are visible after the history lesson even if you go through the glitch to the shrine. They disappear if you go backwards through the main level, either way, so you must (apparently) boost into the glitch from the shrine area in order to see them.
 * No information is available about other levels.