Halo 3: ODST achievements

Found 3 Audio Logs.

Completed Uplift Reserve and unlocked the Dutch character in Firefight.

Found the 3rd clue unraveling the mystery, alone or with another ODST.

Traded weapons with a fellow character.

Got 10 automag headshot kills in any level.

Completed Tayari Plaza and unlocked the Buck character in Firefight.

Found the first Audio Log.

Found the first clue unraveling the mystery.

Accessed and downloaded the city map to your VISR.

Killed 5 enemies while using VISR mode.

Found the first Medical Kiosk and healed yourself.