To defeat Barrett:
- As soon as the battle begins, throw a EMP granade on Barrett (if you have one)
- Strafe/turn right, grab one of the gas canisters on the right
- Throw the gas canister on Barrett
- Run to the left or straight down the right side, grab the explosive barrel, throw it on Barrett
- grab next gas canister or one of the fire extinguishers, throw it at him
- run to another explosive barrel, grab it, aim, throw it on Barrett
- repeat 5-6
- (if you run out of things to throw, Barrett should be damaged enough for you to finish him with any gun)
See the video below for visuals...
Video Walkthrough of the Barrett Fight
Here's quick video showing how to defeat Lawrence Barrett, elite member of a secret mercenary hit squad, and get The Bull achievement.
I used over 45 minutes on the first boss battle of Deus Ex Human Revolution, trying to win the fight with guns, which I hadn't used at all before that as I was playing "stealthily", avoiding enemies by sneaking past them, or taking them down without killing them...
Anyway, after almost an hour I had to give up and I looked for help on how to win Barrett. I found an easy way, which got the job done (even that it was a bit "boring" way to win the fight), but at least I was able to continue this awesome game.
And here's a video I made to show you how to do the same...
Deus Ex Human Revolution Barrett Boss Battle Guide
Watch on YouTube (HD 720p):
How to Beat Barrett in 60 Seconds or Less - Deus Ex Human Revolution - Boss Battle I