The walking dead have been roaming the University of Iowa campus for almost a week since the infection began Halloween night.

The 660 participants — both human and zombie students — are engaged in a universitywide game to survive a week of zombie invasion.

Organized by freshman Joey Hammond and friend and UI junior Ben Pratt, the game was set up through a Facebook event and a website. Once registered, students start as humans, designated by a bandana worn on their arm. If they’re tagged by a zombie, they must move the bandana to their head.

When Hammond brought up the idea to Pratt, his RA in Burge Hall, Pratt was on board immediately.

"I’d never done this before," he said. "We thought to just make the event and go for it."

And so far, it has grown in popularity throughout the week. As of Thursday night, the human-to-zombie ratio is about even, according to the website. Though the game was set to end tonight, Hammond said if the count was still somewhat tied, they may continue over the weekend.

The idea didn’t start at the UI.

Since two Goucher College students thought of the idea in 2005, the game has rapidly caught on at other schools; now, hundreds of colleges participate around Halloween every year. The games have spread as far as Brazil and Europe.

"A lot of people have thanked me and were really excited about the game," Hammond said.

In addition to the Facebook page, the two also created a website on which statistics are recorded about the game, as well as information for current players. And they’re planning for next time — they aim to hold the game once a semester from now on.

"I would like to plan more missions next time, which would make the game more detailed," Pratt said. "Other universities use Nerf guns, but I don’t know if that would be allowed for security reasons."

Humans can use a ball of socks to ward off their zombified opponents, "stunning" them for 15 minutes.

The rules include safe zones inside UI buildings, dorms, and on Cambuses. Now-zombie sophomore Louie Hardin said being undead has its perks.

"When you see someone you don’t know and chase after them or help them find humans, it’s pretty fun," he said. "You also take some pretty crazy routes to class."

Players said their horror stories about being caught by zombies is one of the most thrilling aspects of the game.

"The first day some girl tagged me out of nowhere," said recently zombified freshman Cody Grubbs. "I was disappointed because it happened so quickly."

With several ideas for improving the competition for next semester, Pratt said, this first time around has been a big success.

"People have taken the game really seriously and are having a great time with it," he said.