Here is the full list of all 55 50 years achievements.
Win for russians on very hard (without Chicken Devil help)
Win for russians on hard
Win for japanese on very hard (without Chicken Devil help)
Win for romans on very hard (without Chicken Devil help)
Win for romans on hard
Win for japanese on hard
Win for greeks on very hard (without Chicken Devil help)
Win for greeks on hard
Win for french on very hard (without Chicken Devil help)
Win for french on hard
Complete Plague special game
Complete Heroes special game
Win for celts on very hard (without Chicken Devil help)
Win for celts on hard
Win for egyptians on very hard (without Chicken Devil help)
Win for egyptians on hard
Win for byzantines on very hard (without Chicken Devil help)
Win for byzantines on hard
Win for british on very hard (without Chicken Devil help)
Win for british on hard
Win for americans on very hard (without Chicken Devil help)
Win for americans on hard
Complete Pioneers special game
Complete darks times special game
Confidient win
Complete M special game
Complete invasion of zombie chickens special game
Win for byzantines
Complete 25 years special game
Win for romans
Win for all nations
Pick The Community
Win for japanese
Pick Divine Intervention
Complete brutal force special game
Pick Help of the forest
Win for egyptians
Get three hydras
Get ore armor
Win for celts
Clear all available dens in one game
Get two angels
Pick Chicken devil
Win for greeks
Win for british
Win for americans
Get a unicorn
Win for russians
Win for french
Win without using scrolls
Win for any nation
Reach year 40
Hire 50 peasants
Reach year 25
Clear any den