If last summer’s Xbox Live Arcade releases taught us anything, it was that Microsoft’s Summer of Arcade definitely lived up to its title, and that downloadable games have the potential to be surprise hits. With Summer of Arcade 2009 in full swing, several big-name games have already hit the Xbox Live Arcade, giving gamers some much needed fun during a drought of retail releases. The latest Arcade game, Trials HD, quickly went from being a curious, seemingly simple motorcycle game to a complete obsession. It took me by surprise, but Trials just might be the most addictive and challenging downloadable release of the summer.