I DID IT!!!!!
Bogey Bravo got stuck behind an obstacle and was unable to move out for most of the time, allowing me to kill Bogey Alpha quickly.
Just when I wore Bravo's HP down to half with the Assault Rifle it suddenly freed itself, but with it the only enemy left I didn't find it too hard to use my HMG to keep fighting. Finished it with a boost kick + a few more rounds!
Luck was finally with me, though strictly speaking I didn't really complete the challenge very legitimately.
All my played games have exactly 1000G.
1st 1000G: Batman Arkham Asylum (PC)
1st Xbox360 game: Trusty Bell Chopin no Yume / Eternal Sonata
1st Xbox One game: Child of Light
1st Xbox360 player to obtain Obsessive Compulsive (collect all loots in a single chapter) in Thief on 25/2/2014 at Trueachievements.org
Last edited by ImaginaryRuins; 08-05-2014 at 02:28 PM.