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