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