In the furnace area, you must hold the left mouse button to clean the wall and reveal a code required for a later keypad.
You must collect all 15 notes to unlock "The Librarian" achievement. File: Deep.Sleep.Trilogy.zip ...
For a visual guide, Whiskers' YouTube walkthrough offers a full no-commentary playthrough. In the furnace area, you must hold the
The games rely heavily on environment exploration and item management. Be aware that certain puzzles use that change with every playthrough: In the furnace area
To sneak past the "Bottom Feeder" monster, move your mouse extremely slowly to avoid drawing its attention. Community Perspectives