SERIES PREMIERE: As with many of the shows premiering on this particular date, HBO’s new Game of Thorns is all about cashing in on an existing success. Game of Thrones is one of the network’s biggest successes, but even doing a spinoff with supporting characters would be prohibitively expensive. So ultimately, HBO decided on this 10-part competitive reality series about amateur rose-garden gardeners from around the country – hoping, clearly, that the title might draw in a few extra viewers, whether they be fantasy fans, horticulturists, or dyslexics.