Here is the full list of all 18 Ion Assault achievements.
Finished a stage in less than 90 seconds.
Complete a regular stage without collecting a single Power-Up.
Score exceeds 500,000 points (Survival).
Score exceeds 500,000 points (Campaign).
Destroy five asteroids at once.
Destroy 50 big asteroids in a single game.
Survive 3 stages in a row without losing a life.
Completed the single player campaign.
Destroy seven asteroids at once.
Complete a whole sector without dying once.
Score exceeds 1,500,000 points (Campaign).
Get two extra-lives with a single score upload.
Score exceeds 1,000,000 points (Survival).
Score exceeds 2,500,000 points (Survival).
Score exceeds 5,000,000 points (Survival).
Score exceeds 10,000,000 points (Survival).
Score exceeds 3,000,000 points (Campaign).
Score exceeds 5,000,000 points (Campaign).