I can say with complete seriousness that this is actually what I first thought upon first hearing the title. Since it was Attack on Titan and not Attack on Titan*s*, I'd assumed Titan was a place, and had figured it was some sort of sci-fi anime about a desperate group of survivors trying in vain to defend a lonely lunar colony on Titan against overwhelming odds and struggling to cope with their hopeless situation or something like that. Which actually turned out to not be that far off now that I think about it.