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