Here is the full list of all 12 Outland achievements.
Complete any Arcade Chapter below the target time (General)
Defeat any boss without taking damage (General)
Complete the full game (Individual)
Destroy six enemies with one Beam Shot (Individual)
Collect 10 Marks of the Gods (Single Player only)
Destroy an enemy using a Kamikazer (General)
Destroy a Spider using spikes (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)
Collect all Marks of the Gods (Single Player only)
Collect 1,000,000 Doubloons (Single Player only)