Here is the full list of all 11 Tiamat X achievements.
Level 1 completed
Completed a level without losing a life
Level 2 completed
Level 3 completed
Level 4 completed
Level 5 completed
Level 6 completed
Completed the game
Completed the game without losing a single life
Killed all enemies on a level
Completed a level firing only the minimum amount of shots to get the job done