Can the Test of Faith achievement in Mirror's Edge be done piecemeal?

Question

Test of Faith is the achievement for completing the game without shooting anybody.

I completed the game and was careful not to shoot anyone, but did not get the achievement. So I was wondering if I could go back and play a chapter where I might have shot someone and still get the achievement?

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Additional Info

The only time I fired a gun aside from the time that you have to shoot the caravan, was when I was fighting two guys at once, disarmed the first one and went to attack the other one in melee but my attempt to drop the weapon I took from the first one didn't work, so I ended up shooting him. I then let him kill me (the shot didn't kill him) so I hoped it wouldn't save that.

So I was hoping I could go back and just replay that chapter and get the achievement... but that didn't work either.

So basically I think the answer to my question is no, you have to play straight through it without ever shooting anybody, but I thought I'd put it out there and see if anybody knows any different.

Answer 1

I believe you need to play through the entire game without shooting anyone to gain this achievement. If you mess up, you can reload your last checkpoint and go again but if you've passed another checkpoint since, you'll need to restart.

If you want to check as you go along, you can press the "Back" button and in the top-right of the screen it should say: "So far, you have not fired a shot at anyone". If you think you may have shot someone, hit the "Back" button and check this. If it's gone, you need to reload your last checkpoint. If it's there, you're good.

The bit with the convoy doesn't count as a shot and you can actually shoot guns in the game (at servers etc), as long as you don't shoot at anyone.