Humans Vs. Zombies started on our campus about 5-6 years back. Popularity seems to wax and wane, and a majority of the interest comes from a relatively limited number of people (based on when some of them graduate), but it generally seems to have at least 20-30 people every year.
Part of the reason for this, I think, is that they ask everybody to kick in $5 for the bandanas, and then they donate the extra to help fund brain cancer research, so it has a nice community service element included. The marshmallows (human ammo) are bought at the humans' discretion and on the humans' dime.
Here, the event lasts the better part of a week, usually, giving zombies a whole day to feed before dying off (and last year they introduced the "Super Zombie," as a way for "deceased" zombies to survive by eating other zombies), and the game goes on until the last human is eaten, or the last zombie starves. They also keep statistics on a blog that updates daily, so people know who to avoid and who is safe.
And speaking of safe, certain areas are declared "safe zones," since the game lasts for so long. Generally speaking, the library falls under that canopy, so while waiting for someone on the steps is perfectly acceptable, you can't stalk someone to their study carrel and get them while reading up for their Organic Chemistry exam. This was decided after the first day proved that it was far too difficult to both play and remain a student. A one-day event probably wouldn't have the same limitations, but bathrooms and the areas immediately surrounding them should probably be granted a safety restriction, considering the situation.