Minitrain

A network of railway service tunnels between the Central Water Plant and Central Metro Station. This map mostly features steam-valve puzzles, and plenty of photographable spots. The minitrain featured in the level isn't required to progress in the map, but can save the player a lot of walking.

Story
As usual with the Stalburg's tunnel system, many tunnels have flooded, whether neglected over the years or from the Bergmann tunnel collapse. The concrete structure has developed faults, green mushrooms have infested a sealed off area, and some steam pipes sprung leaks in a crawl space maintenance area, recently inhabited by the homeless.

After Mark's departure from the Central Water Plant, he journeys through the tunnels via minitrain in attempt to get back to surface level, facing various obstructions and avoiding yet another collapsing hallway. When the minitrain reaches the end of the tracks, Mark opts to enter a nearby ventilation shaft that connects directly to the Central Railway Station.

Minitrain Tunnels
The tunnels beneath Stalburg are extensive but poorly maintained. There is a small network of rails and other minitrains used for transportation. Parts of these tunnels are recently developed and in better shape than the older and decrepit tunnels, some of which are dug straight into rock without supports.

Trivia

 * The notepad with several door codes contains the code for the keypad puzzle in the next map.
 * There is an out-of-bounds easter egg adjacent to the tunnels. This room holds a table, with five chairs occupied by live crow, a working desk fan, a dragon doll, a teddy bear with a Mörkö mask on it, a singular boot, a 10 liter canister of Pontikka, and a wet floor sign. The wall dons a large Osmo Olut sign. On the table is beer, an 24-pack of Osmo Olut with a bomb coming out of it, and a newspaper about disappearance of Jeff Walter.