Here is the full list of all 12 Choplifter HD trophies - there are 7 bronze, 4 silver and 1 gold.
Complete the game on NORMAL
Get 5 stars on all the levels
Complete all "Escape" missions without killing anyone
Kill 100 enemy soldiers on one level, without restarting the level
Complete a level by killing all the rescuees
Kill 10,000 enemies across all the levels
Complete Desert Rescue without letting any rescuees die
Save Scoop on every level he is present
Find all the secrets
Kill 1000 chickens
Kill 1000 zombies
Kill 100 goats