Party mission: Go to the underground UNATCO ruins on Liberty Island. Take the U.N. flag from near the beginning of the ruins and find your way to to James Manderley's office from the first Deus Ex. Hold the flag while flushing the toilet inside the bathroom to play the programmer's party mission. Thief 3 preview: Successfully complete the game to unlock a preview of Thief 3 in the "Extras" option.