Be Like Marty
From Halopedia, the Halo wiki
Be Like Marty is an achievement in Halo 3: ODST when you finish an entire round on Firefight without killing an enemy. It is worth 10 Gamerpoints.[1] The name of the achievement is very likely a reference to Martin "Marty" O'Donnell, the musical composer for the original Halo trilogy. This Achievement was confirmed in a comment in the 7/7/09 Bungie Podcast, presumeably along with the rest of the leaked list.
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