The Bureau Xcom Declassified: Alternate Final Guide [360-PS3-PC]
Surely you already know that The Bureau Xcom Declassified matters well 4 alternative endings. The ending you get depends on the choices you make from a specific point in the game.
ATTENTION! SPOILER !!
Towards the end of the game, at the XCOM base, the captured ethereal, Shamash, psionically contacts the Ethereal inside Carter, Asaru. Shamash argues that since both the Outsiders and humans have learned how to capture the Ethereals, they must be destroyed so that a force like Mosaic will never be rebuilt. Hearing this, Carter tries to free himself from Asaru to kill Shamash. The XCOM base is discovered by the Outsiders, and Carter tries to defend it, while trying to free himself from Asaru's control. Carter manages to plant an explosive device with a 30-second timer, believing that Ethereal will never allow him to go free.
The choices made from this point on determine which of the 4 endings you will get. Here are some videos showing all four of them, enjoy.
Finale William Carter
Final Director Faulke
Finale Angela Weaver
Finale Dr Weir