I wouldn't say it was that similar to 28 Days Later, but it was a lot alike the Road. Thing is, there was enough to differentiate it IMO that it could become a hit as a movie. And audiences have made movies that fit exactly what you described into megahits before even if it doesn't. But I think a zombie movie that focuses on a surrogate father/daughter relationship rather than the zombies is just different enough to work as a movie, especially since both are well developed characters. I will say that most video game stories are generic, but there are ones with great original stories and ones with good enough ideas to justify a movie adaptation.