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)
Destroy an enemy using a Kamikazer (General)
Smack a bomb so that kills two or more enemies (Individual)
Collect 10 Marks of the Gods (Single Player only)
Destroy a Spider using spikes (General)
Kill 20 enemies in a row with only 1 health left (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)