Or how about this....
You receive a colour invitation, by post, to a Murder Mystery evening hosted by one of your friends (but you don't know who!) at a location to be revealed at a later date.
Included with the invitation is a Character name and Password to be used on a website where more details of the evening and the special tasks will be revealed.
Having logged into the website, more teasers are given, more information on the location, clues to who else will be attending, what needs to be worn and prepared is also offered (not all at once though!) this will be drip fed over the weeks, at set times, however at no time will the organisers identity revealed.
Tasks may be asked of the guests e.g. to prepare one or more of the courses, or perhaps to bring certain objects (some of which may be red herrings!)
As the date draws in, additional information may be released enhancing each guests knowledge of their character or advising the guest of a task, this information can be freely discussed between the game players, (once they have established who they are from the clues once they have accepted!) thus building the intrigue even more.
Still no clues for the location and certainly none regarding the organiser!
Five days before the big day a clue is posted on the website regarding the venue, this is added to on a daily basis until four clues have been released.
The day before it is 'all due to happen' the actual venue details are posted.
The evening then takes on the 'normal' schedule for a Murder Mystery evening.
At the end of the evening, it will be down to the organiser to reveal (or not) what they had done!!!!

All the time you the organiser will be having your own private piece of the fun
You will have access to an admin page. This page will track all the times\dates and pages
your friends have visited the site - you'll be surprised at what times they check
the site and just how frequently!!!!