If your enjoying your copy of Batman: Arkham City and hoping to collect every achievement/trophy, then a quick head’s up at something neat to do tomorrow. The first day of the “Storyteller” achievement/trophy is on Halloween.
Calendar Man is still locked up in the basement of the Solomon Courthouse and for players to legitimately get the the achievement, they need to visit him on 12 different holidays that he has marked on the calendar next to his cell. He also reminds you of the next day when you ask him. I know that you could do some funny things with your console’s clock to get the achievement/trophy, but if you’re like me and not planning to cheat to get the Easter eggs, then make sure to visit Mr. Day and see him regale Batman with his horrific tales of holidays past.