The Xbox 360 port of Minecraft was the most popular XBLA game during the one week period beginning May 7, according to Major Nelson. Minecraft also pulled into a respectable third on the overall list of most-played 360 games last week, behind only the ludicrously popular Activision FPS duo of Call of Duty: Black Ops and Call of Duty: Modern Warfare 3.
Originally released on the PC by Swedish developer Mojang in alpha form way back in 2009 before having the full version become available in November of last year, the world-building title was brought over to Arcade by 4J Studios with the help of its original developer and Microsoft. The port eclipsed the one million sold mark on May 14, at which point players had sunk in excess of 5.2 million hours into the game.
Source: Major Nelson