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