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