Developers of such maps often use "fullbright" settings or stark, unnatural lighting to bypass the engine's realistic shadows, contributing to the flat, surreal look characteristic of dreamcore.

The file appears to be a Source Engine map file (likely for Garry's Mod or Half-Life 2 ) associated with the "Croject Papture" series, which is known for its surreal, dreamcore, or "weirdcore" aesthetic . Article Overview: Development of Croject Papture.bsp

While Source is a 3D engine, these maps use teleports and looped corridors to make spaces feel larger or more confusing than they are.