In terms of direction, I believe I found a starting point. The game'll be a survival game themed as though it was from an 80's action film, I initially thought taking it down a more kid friendly root and have the main character as a kid genius; changing the whole mood of the adaptation.
I stumbled across something while researching called Retro-futurism, it's pretty much the future envisioned through the eyes of someone from as far back as the 1960's. A main thing I wanted to do seeing as I Am Legend has dystopian themes was to have it set in the future and a retro future zombie game sounds different enough it kind of moves away from genericism.
...and here's my current Inflence Map
....and initial doodles