Here is the full list of all 23 Foreign Legion: Buckets of Blood achievements.
Kill 2500 chickens
Play a game with only the Night Vision Goggles equipped
Play a game with only the Peace Badge and Bullets equipped
Kill 25 chickens
Play a game with only the Smiley Badge equipped
Kill 5 enemies with an air raid
Reach level 20
Kill 1337 enemies in total
Kill 4 enemies with one rocket
Survive 30 minutes in endless mode
Repair the town hall 5 times in one round
Kill all enemy waves in 7 minutes
Find the minigun
Beat the Village in the extreme difficulty
Purchase the Foreign Legion FAMAS
Finish the campaign on any difficulty
Destroy the supreme chicken overlord
Make 15 headshots in one round
Purchase an outfit, helmet and accessory
Escort the bus safely without it taking damage
Win the game with all civilians alive
Make a kill chain of 10 kills
Kill all chickens in one round