In this new XCOM: Enemy Within trailer from 2K and Firaxis Games, deadly new enemy units have been deployed to the battlefield, yet a newly discovered alien substance brings the opportunity to augment your soldiers with biological or cybernetic enhancements. These soldiers sacrifice much, but gain never before discovered combat effectiveness. It’s your decision, Commander.
PAX 2013: XCOM: Enemy Within to Be Shown
Gamescom 2013: XCOM: Enemy Within Announcement Trailer And Screens Preview