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