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