Well, it looks like it's sometime listed as Horror or Thriller. So that doesn't really help. Has anyone watched this one?

I think its better to be on the safe side and add the horror genre. Now someone even added a keyword named horror, which should be in the genres. A movie about aliens and zombies.

I've watched it and to me it's not a horror movie. I think it's fine to keep it at two genres, but if we have to add one more genre thriller is better. And to explain, for me horror indicates that you get scared in some way, while thriller describes a more general apprehension (if that makes sense). And I know experiences may differ from person to person...