Here is the full list of all 11 Alien Zombie Megadeath trophies - there are 5 bronze, 5 silver and 1 gold.
Unlock all of the extra Spacesuits.
Get a combined total score of 30 million on all levels.
Unlock the UFO upgrade.
Unlock 20 levels.
Get a combined total score of 3 million on all levels.
Score 2 milion on any single level.
Unlock one of the extra Spacesuits.
Complete the introduction training level.
Unlock all the levels.
Complete all the adventure levels. The blue ones!
Easy! Collect all the medals.