I'm going to be making a I AM LEGEND based campaign. It's a mix of the novel and the movie.
Basic idea is that the virus only affected North America and it was quarantined for 5-10 years (havent decided yet)
Nature has - for a good portion of the land - taken back over. Animals that once were only in zoos or were quickly going extinct now floruish once again. The various styles of vampires (the nutjob ones, the intelligent civilization creating ones, etc) live in different sized cities/villages etc. and luckily have learned from the past and have left most of the land alone. If you've seen the movie, imagine it sort of like that when it comes to nature.
After many years the quarantine has been lifted solely for military and research teams. However, curious folks from all sectors of life are tempted to sneak in, and many do. The player characters are a combination of illegal explorers going to explore the new version of the once modern North America.
That's the short of it.
So, I'm debating what system to use for this? I want something crunchy - being a campaign and all - and something versatile. I have never read any of the WoD stuff and I'd really rather not use d20, but I will if it comes down to it, and I may try using GURPS4e, but I wanted to see what everyone's opinion would be.