Here is the full list of all 64 King Arthur's Gold achievements.
Return your team's flag 5 times
Get 50 stomp kills
Blow yourself up as well as the enemy using a bomb
Kill the enemy flag carrier 10 times
Steal an enemy's mine
Launch another player from a catapult 20 times
Kill whole enemy team in TDM (at least 3 players)
Win 100 matches
Get 500 kills
Make love, not war
Get launched from a catapult 20 times
Get killed with a pickaxe 20 times
Eat a flower
Commit suicide
Cap 5 flags
Take a nap in a quarters
Use water arrows 20 times
Join a modded server
Use fire ammo 20 times
Remain the last player alive in a TDM match
Win 10 matches
Reach 500 coins at a time
Buy something at an enemy shop
Get a kill with each class in the same round
Sushi!
Get a kill on an enemy while dead
Kill someone using a fire arrow
Get killed with an arrow 20 times
Switch teams
Get 50 kills
Win a match
Get killed with a sword 20 times
Design and arrange a shrub
Get a kill while on fire
Defuse a mine
Use chat
Join multiplayer
Get 5000 kills
Get a bomb kill as an archer or builder
Get 5 kills with the drill
Run over an enemy with a vehicle
Get a kill by launching a boulder from a catapult
Kill a player with a boulder 5 times
Kill an enemy with a tamed shark
Kill 3 people with 1 bomb
Kill 5 enemies with 1 keg
Cap 20 flags
Return your team's flag 20 times
Take 10 halls
Take 40 halls
Save the Princess
Kill the Princess
Complete 10 Challenge mode maps
Ride your tamed bison
Use all animals in game
Test the air-speed velocity of a laden chicken
Catapult a shark
Ride in every vehicle
Carry 4 burgers in your backpack at a time
Carry all 4 kinds of arrows
Go down with a sinking warboat
Heal an ally with a burger
Man them!
Capture 5 warboats