There's nothing overly complicated here. You just explore a maze, and must find the exit to win the 'game'. Sure, there's a few twists and turns along the way, as well as a creepy atmosphere, but I assure you as an explorer; this is just a maze. There's nothing sinister going on in the darkness. Nothing.
This is one of the many hallways, though this one in particular is accessible near the spawn location. Each hallway in the game will be slightly different, and represent various 'zones' that you can explore in the game. Blue, as pictured here, indicates that the player is in the 'water' zone.