The Special Edition Add-on for Mark of the Ninja has 8 achievements worth 100 gamerscore.
Disable a spotlight using the Dusk Moths.
Read one of the history lesson developer commentaries.
Complete one of the original Mark of the Ninja levels using the Path of Wisdom.
Stun an elite guard with moths then dispatch him.
Dispatch two enemies at once using a body infected with Toxic Fungus.
Complete the new Special Edition level.
Knock out an enemy again that was revived from being knocked out.
View any of the developer commentaries.