Initially designed as an FPS, the game is now a third-person tactical shooter called The Bureau: XCOM Declassified.
It will be released on Xbox 360, PS3 and PC on August 20, 2013 in North America and August 23 internationally.
Set in 1962 at the height of the Cold War, the title is in development at BioShock 2 studio 2K Marin.
The game's release had been called into question after it suffered a string of delays.
Creative director Morgan Gray said today of the revamp: "The Bureau tells the story of XCOM's mysterious beginnings. We're expanding the universe with a declassified tale of government conspiracy and heroic cover-ups told through third-person tactical gameplay.
"The team has been working hard to leverage core XCOM elements like tactical decision-making and permanent death of squad mates in a purposeful way that makes this a unique tactical shooter. To that end, The Bureau will challenge players unlike any other third-person tactical shooter."
Pre-orders will grant players access to the 'Codebreakers' add-on, a campaign side-mission in which players are sent to investigate a communications facility that has gone dark.