[ADDED] Archimedes

After you purchase and install Archimedes, an old operating system appears to be running, and a strange man asks for your help as you start to discover the terrible secrets behind the game.

You will be required to interact outside of the game, with instances ranging from steganography and cryptography to real-world geographical puzzles and use of various external applications. The deeper you go, the more frightening and personal it will become.