To me this sounds a lot like the Torch Competition... Which for me was rather confusing and irritating.
I would want to make a few changes, if it was me. First, people should know they are signing up for it. I didn't even mean to sign up for the torch contest. I clicked to read more and bam! I was signed up without a way to back out. And no, you shouldn't be able to back out once you sign up unless you have a really good reason to, but it should be much more clear, like have all the info about it clearly laid out with a link to someone to ask questions about it if need be and have them say somewhere, "I, blah blah blah, want to compete in this competition/game/whatever".
Second, I would try to make the teams much more even. Have an even amount of mp3 on each, mp4's, ect or at least attempt to and then even go as far as trying to make sure there are an even amount of people from each similar time zone on each to make it even more fair and easy to play. It isn't fun if your team can't really find any one to play with after all.
Third, I would personally recommend that no one could turn on their team. Someone joins and decides they don't like it and want to sit out, fine... But you shouldn't get to tuen and start attacking your own team members. This could probably go with my second point. maybe if people had more of the other team to play with then they wouldn't feel the need to attack their own for points? Maybe.
Fourth, I would want to know who is on my team and who is on the other. I'm not sure if there had been lists with the torch competition but if there were, I couldn't find them and I had looked. I would click on every one I passed to see if I could tell if they were on any team and if they were, which one. It seemed like a huge scrambled mess. And one person even said he was one color but had a torch of a different color making him look to be the alternate color. I would want to avoid this as much as possible. And also, if it does work like a torch, I would still like to be able to message them. I found I was unable to message anyone holding a torch. But this could have been a bug, I'm not sure.
Lastly? I don't like the idea of Zombies. Like others have said, it seems very un-MD. What if it was creature versus creature? You could still have two teams, Team A being Archers and Team B being Aramors. Or something along the line. Everyone playing could even get a picture of the creature they are as their avatar. I think what could further the experience even more would be to choose a place, maybe even the maze. Lower the viscosity and rope it off to the players playing the game only for a set amount of time. Maybe a week. And everyone playing gets their name and avatar and tags stripped for the duration of the game so all you see is what the creature would be. Better yet, have it illusioned so that the enemy only appears as the creature but you can see your teammates to make for better planning. But to also limit working with the enemy to turn on your team. I think it would also make things more fair. If player A hates player B, he may try to target only player B. But if player A doesn't know which person player B is? He can't do that. But then, maybe that would be too difficult to supplement?