Debuting a new television series is hard enough. But when the new show requires viewers to familiarize themselves with a mythical land, dozens upon dozens of characters, intricate maps, and confusing power struggles, it's a steep marketing hill to climb. HBO's Game of Thrones, which premiered last Sunday, is such a show in that it asks viewers to embrace the complex world of Westeros. The biggest challenge? Getting potential fans up to speed. Instead of relying on the usual advertising conventions of television commercials, print ads, and billboards, HBO thought outside — and inside — the box.