The Clue!
Press Keyboard right side: Alt+Enter keys to switch to full screen game play, and Alt+Enter keys to return.
How to play The Clue!
Press enter at password screen to bypass protection :) Each game uses different controls, most DOS games use the keyboard arrows. Some will use the mouse.
The Clue! Description
The Clue! (known as Der Clou! in Austria) is a remake of the 1986 game They Stole a Million. It would form a two game series, with a sequel following in 2001, under the guise of The Sting! or Der Clou 2!.
An adventure game, assuming the identity of Matt Stuvysant, a burglar who is looking beyond just the clothes on his back and a hotel room on Holland Street, the player is tasked with finding accomplices, scouting potential targets, and plotting plans of burglary, down to the finest detail. Featuring the archetypal point-and-click interface during investigations, engaging in planning a job would alter the controls to include keyboard, using it to control the planned movements of the personnel.

The Clue! - additional information
