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