Full list of all 15 Marathon: Durandal achievements worth 250 gamerscore.
The base game contains 12 achievements worth 200 Gamerscore, and there are 2 DLC packs containing 3 achievements worth 50 Gamerscore.
Read every single terminal in the game.
Completed the Citadel.
Slaughtered 77 Bobs.
Beat the game.
Punched all switches, played on Total Carnage and never ever left a single Bob alive.
You are a member of the 7th Column.
Toasted 20 opponents.
Killed an invincible opponent.
Won a Multiplayer game.
Spank'd 20 opponents.
Punched seven enemies to death.
Got the Assault Rifle.
Outscored every other player combined in King of the Hill or Kill the Man With the Ball.
Killed a Juggernaut in Survival and lived to tell the tale.
Won a multiplayer game in every map in the Total Carnage Netmap Pack.