Xbox LIVE Arcade title Defense Grid: The Awakening is this month's first free Xbox LIVE Gold game - which is a bit of a shame if you were expecting Halo 3 or Assassin's Creed 2, I guess.
Defense Grid is the second title to be released under Microsoft's new 'Games With Gold' program following last month's Fable 3. The title usually costs 800 Microsoft Points.
Games With Gold was announced during last month's E3 and offers Xbox LIVE Gold users two free games each month, with a new title launching on the 1st and the 16th of each month.
The initiative has presumably been launched to counteract Sony's PlayStation Plus program. One appears to offer slightly more value than the other, however.
This month, PlayStation Plus users can download Uncharted 3: Drake's Deception, XCOM: Enemy Territory and LittleBigPlanet Karting entirely free of charge, with Battlefield 3 and Saints Row: The Third set to follow later in the week.