Plenty of games have stories with faulty logic in them, but those who've played it know I'm picking on Fallout 3 here.
Fallout 3 is one of my favorite games of all time, and there are side quests in it that showed me the moral dilemmas possible in video games, showing just how short Fable actually fell from the goal.
But this one side quest made no sense. The whole reason they're attacking this "town" is supposedly because of a desire for blood, but they don't get blood from the attacks. They mostly make noise and trash the place while people hide indoors.
It's said towards the end of the quest that, if they don't attack that town, they'll have to attack a different town. But if they're not drinking anyone's blood, then the desire for blood isn't really being addressed, so they're just doing it to be trolls, and yet it's something that has to be addressed to complete the quest, and...
Also, you have people doing the whole "we've decided to be vampires thing", and not one of them has a prewar vampire costume you can get off of them. The apocalypse happened in late October. The odds of scavenging up a costume were about the best they could possibly be.