The 7th Guest

The 7th Guest was a first person horror adventure game where you enter Stauf's mansion and have to solve the riddles of the diabolical machinations inside.  It was released for DOS, CD-i, and Mac in 1993.  It was later released for iOS on December 15, 2010, and updated for modern systems, including Windows, OS X, and Linux on October 19, 2013.