Here is the full list of all 11 Action Legion achievements.
All intel collected
Game completed in HC mode
Complete HC mode without any casualties
Complete all missions in HC mode in par time or less
Congratulations! You just completed the game.
You have just killed 500 enemies!
Thanks to you the tribal elder lives another day
The first major encounter completed
Squad has been killed quite alot now..
Congratulations! You have completed the first mission
You got your whole squad killed! Well done!