Here is the full list of all 17 Halfquake Trilogy achievements.
Destroyed the first iteration of Somos. [HQ1]
Terminated the second iteration of Somos. [HQ2]
Killed the third iteration of Somos. [HQ3]
Successfully defeated a mighty dragon. [HQ2]
Received a free cookie. [HQ3]
Walked through the abandoned melody tunnel below the grass field. [HQ3]
Patience is called patience because you'll need about twenty minutes of patience. [HQ2]
Found the secret area in the very first level of part one. [HQ1]
Found the maze below the maze. [HQ2]
Found a secret in the first room of the third part. [HQ3]
Uncovered a secret stash of replacement buttons. [HQ1]
Activated a fifth music layer. [HQ2]
Heard a serious warning signal shortly after hearing about the Jumping™ ability. [HQ3]
Found a secret area instead of dying by choice. [HQ2]
Found another secret area after "jump and run". [HQ1]
Jumped despite being told not to do so. [HQ2]
Mastered the dance machine. [HQ3]