The classic board game by Hasbro is now online as an advergame. It's a lifetime I don't play the real Cluedo, so I didn't try very hard to remember the mechanism and play it online. In any case I must say the game looks pretty good, nicely designed and quite engaging as any classic game usually is (otherwise it wouldn't have become a classic). The added value is that players get extra bonus points if they get the clues from the real world (for example related to the Cluedo box).
There is also a contest connected to the virtual investigation, you have time until October 25th to solve the mystery.