Full list of all 49 Mass Effect achievements worth 1,200 gamerscore. It takes around 60-80 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 45 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 4 achievements worth 200 Gamerscore.
250 synthetic enemy kills
Complete Virmire
75% of total Paragon points
Resolved impossible situation with Charm or Intimidate
Exceed 1,000,000 Credits
Found Liara in Artemis Tau Cluster
150 Assault Rifle Kills
150 organic enemy kills
Complete Noveria
Land on an uncharted world
Find all primary Alien: Council Races, Extinct Races and Non-Council Races codex entries
Player is Spectre
Complete Eden Prime
Complete 1 Mass Effect Playthrough on any setting
Complete Feros
Complete 2 Mass Effect Playthroughs on any setting
Complete 1 Mass Effect playthrough on the Hardcore difficulty setting. Do not change the setting.
Complete 1 Mass Effect playthrough on the Insanity difficulty setting. Do not change the setting.
Register 150 Pistol Kills
Register 150 Shotgun Kills
Register 150 Sniper Rifle Kills
Use biotic Lift 75 times
Use biotic Throw 75 times
Use biotic Warp 75 times
Use biotic Singularity 75 times
Use biotic Barrier 75 times
Use biotic Stasis 75 times
Use Damping Field 75 times
Use AI Hacking 75 times
Use Shield Overload 75 times
Use Sabotage 75 times
Use medi-gel 150 times
Use Neural Shock 75 times
Complete the majority of the game
Complete playthrough with shield damage greater than health damage
Complete the majority of the game with the Alliance soldier squad member
Complete the majority of the game with the Alliance sentinel squad member
Complete the majority of the game with the krogan squad member
Complete the majority of the game with the turian squad member
Complete the majority of the game with the quarian squad member
Complete the majority of the game with the asari squad member
Reach 50th level with one character
Reach 60th level with one character
Accumulate 75% of total Renegade points
Complete any romance subplot
You completed the Bring Down the Sky mission.
Complete Ahern's survival mission
Take first place in any combat scenario on Pinnacle Station
Take first place in 12 combat scenarios on Pinnacle Station