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