Here is the full list of all 9 R.A.T.S. (Regulatory Astro-Topographical Stabilizer) achievements.
Die on the first level
Fully upgrade one of your ship's weapons
Defeat the first boss
Defeat the final boss
Earn all stars on all levels
Have 150 enemies die to environmental hazards
Kill 250 Bomber enemies using the Spread-Shot gun
Kill 150 Dodger enemies using the Homing Missiles
Destroy 200 mines with the Lazer-Whip gun before they hit you