The first Xbox Live Games with Gold title is Defense Grid: The Awakening. The Xbox Live Arcade title normally costs 800 Microsoft Points ($10) but is free for Gold members from July 1 to July 15.
We previously reported that Halo 3 and Assassin's Creed II would kick off the twice-monthly free games program, but that was evidently a mix-up. Microsoft mentioned both titles would be featured when it debuted Games with Gold, but did not say they'd be the first two to appear.
Xbox Live's Larry "Major Nelson" Hryb apologized for the disappointment in a Reddit thread about the title, where several users complained about the relatively low-profile game compared to some of PlayStation Plus' offerings.
"I don't work in marketing, but I am going to make them aware of this thread," Hryb wrote.
The program is slated to last through December 2013, though Hryb said it may last longer if it fares well. Either way, you don't have to remain a paid member to play the games.