Here is the full list of all 12 Outland achievements worth 200 gamerscore. It takes around 8-10 hours to unlock all of the achievements on Xbox 360.
Complete any Co-op Challenge Room (General)
Collect 1 000 000 Doubloons (Single Player only)
Defeat any boss without taking damage (General)
Complete the full game (Individual)
Collect all Marks of the Gods (Single Player only)
Kill 20 enemies in a row with only 1 health left (Individual)
Complete any Arcade Chapter below the target time (General)
Destroy six enemies with one Beam Shot (Individual)
Smack a bomb so that kills two or more enemies (Individual)
Destroy a Spider using spikes (General)
Collect 10 Marks of the Gods (Single Player only)
Destroy an enemy using a Kamikazer (General)