As said before, very creative, but might be a little too controversial and insensitive to my tastes...
You know what would make this game playable? Zombies. Titanic is sinking because an iceberg carrying 1,000 zombies hit the ship. The zombies, not being very smart, figured it would be a good idea to ambush unassuming warm bodies with a rather unmaneuverable ice berg. It finally paid off, and now they are on a feeding frenzy, so you now must survive a sinking cruise ship in icy waters AND ravenous zombies chasing you through the ship... while avoiding packed corridors of panicking passengers.
A Hurricane hits the south-east of the United States, and, within it's clouds, are zombies... who are rapidly deployed via... THE SKY!
Earthquake hits Mexico... zombies crawl out of the cracks in the earth, feast on humans and salsa verde.