One shot game ideas / Brain dump

I often walk around with game ideas gestating in my head, most of which never come to term, and those that do are often born baring little or no resemblance to the inspiration that conceived them. The bastard offspring of necessity and circumstance rather than the planned child of vision and inspiration.

So, after that rather turgid and overly long metaphor, what I intend to do with this post is record some of these game ideas for future generations. Seeing as the practice rarely resembles the theory, I'm not too worried about potential players getting advance warning. They usually cause deviation and upset within half a session without prior knowledge.

Summary: zombies lay siege to a gated community
Here's what I'm talking about when I say 'gated community'
http://en.m.wikipedia.org/wiki/Gated_community
One of the virtual fortresses with defensive walls, full time security staff and exclusive residents.
The set up: It is Bob and Lorrain  Danver's silver wedding anniversary. They are having a massive party at their home in Range Point Gated Community, and have invited dozens of guests - friends, family, work colleagues, country club tennis buddies, water buffalo lodge members, mothers circle members, neighbours and local businessmen. It's a huge blow out with professional caterers and a free bar, a jazz band, string quartet, ice sculptures and a guest appearance by a pro golfer.
As the party goes on into the night, the normal dramas and exchanges play out: family politics, illicit liaisons, business networking, drunken brawls, tears and laughter, before finally coming to a sudden halt when Bob keels over from a massive coronary.
Everybody stares. Everything stops. Somebody screams and Lorraine rushes to his side. One of the guests, a doctor, examines Bob and finds no pulse.

As people start to dissipate, and as several guests attempt to call cabs or an ambulance, several things come to light.
There is no mobile phone service. Network error. Network error.
The gates to Range Point community are locked, and the security guard is missing.
There are several homeless people milling about outside.
TV news stations are covering mass riots and gang violence across the country.

Shortly afterwards, Bob gets up and attacks Lorraine.
The dead have risen and are attacking the living.
The residents of Range Point, the party guests, party staff and community security are trapped in the community. They are safe for now, but have limited supplies of food and water and medical supplies.
What do they do? Wait it out or leave the safety of Range Point.

Players can play a resident, a party guest or staff.

The game would use the World of Darkness rules

Edit...
If you're planning a zombie holocaust, then see if you can get a copy of Hunter: the Vigil, which has a whole chapter on Morality and killing monsters.
My tips for dramatic Morality tests would include:
Accidentally killing a human being Having to kill somebody who's been bitten but not yet turned
Having to leave someone behind to die horribly to save someone or something else
Stealing supplies from other survivors. They need it. You need it. You're not them...
Having to kill somebody who's been driven mad by the horror (like Tim Robbins in War of the Worlds)
Not destroying a zombie, and learning that zombie has killed somebody close to you