Here is the full list of all 8 Astro Tripper achievements.
Destroy the Boss without opening more than one outer door. Only 1 of the 3 outer doors may be opened to any degree.
Complete level Fizz Wheels without killing a Fizz Wheel, ( the rolling wheels connected by a laser ).
Destroy 3 Worms in sequence on The Ooze.
Destroy 20 tanks in sequence.
Destroy 3 Flypods within 5 seconds on any level of Insect Infestation.
Destroy the Spider Boss on Arachnophobia, without destroying any of its mini guns.
Destroy both generators on Claustrophobia without killing a Tank.
Destroy 10 mutated pods in any one level of Training Grounds.