I would love to commit to this so I'm throwing in my interest. I really like both elements that you have come up with and I think it would make for a story that suits me. So I would like to register myself in for this. It's a good introduction and I can't wait to see it come to fruition.

I think it would be interesting with the time machine aspect to explore how much could really be changed. I wouldn't be averse to the possibility of a bad ending, or perhaps a pyyrhic victory type idea, where humanity is, instead of saved, still forced to go through the apocalypse but not as badly threatened with extinction, or some other kind of bleak outlook.

Of course, with the zombie thing being typically a plague I definitely think that the usual route for the end-game would be preventing the research of a cure for a disease or something along those lines. We'll have to see if that's what people decide on but I wonder if that would be considered too cliché for this story, and if we want to go for something different.