Here is the full list of all 12 Alien Attack: Pocket Edition achievements.
Kill one alien!
Die one time!
Achieve 100 score points!
Kill 500 aliens!
Kill the second boss!
Achieve 500 score points!
Kill 2500 aliens!
Die 50 times.
Kill the third boss!
Kill the fourth boss!
Kill 5000 aliens!
Kill the final boss!