Here is the full list of all 13 Alien Zombie Megadeath achievements.
Complete all the adventure levels. The blue ones!
Unlock all of the extra Spacesuits.
Unlock all the levels.
Get a combined total score of 30 million on all levels.
Score 2 million on any single level.
Get a combined total score of 3 million on all levels.
Get the multiplier to x10
Unlock the UFO upgrade.
Unlock 20 levels.
Unlock one of the extra Spacesuits.
Get the multiplier to x5
Complete the introduction training level.
Easy! Collect all the medals.