Here is the full list of all 45 Gunman Tales achievements.
Win Stage 6
Kill 1K Enemies
Win Stage 11
Win Stage 12
Shoot the Chicken 100x
Win Stage 10
Make 100x Combo!
Obtain Boots of Haste
Win Stage 1
Kill Your First Enemy
Bring a curse of "horse poop" upon yourself!
Slay the legendary Werewolf
Find the Legendary Lost Treasure!
Die 100 times
Find the outlaw Dirty Willy and bring him back ...DEAD OR ALIVE.
Drink 10x Firewater
Finish the Game
Find All Pieces of the Map
Use Medallion of Luck 10x
Drink 10x Health Potion
Drink 10x Antivenom Potion
Visit the Old Mine 100x
Use Old Spyglass
Rest 100x in Your House
Throw 100x Dynamite
Visit 100x One of the Two Cities
Eat 100x Mushroom
Gather 1K Dollars
Visit the Saloon 100x
Donate 100 Coins for the Doctor
Visit the Indian Shaman 100x
Win Stage 2
Win Stage 3
Win Stage 4
Win Stage 5
Win Stage 7
Win Stage 8
Win Stage 9
Destroy 10 Cow Skull
Shoot the Goldfish 100x
Let Yourself be Killed by a Werewolf
Find the Alien Corpse
Catch the 50 Cows
Finish the Game on the "ThumbSucker" Difficulty
Finish the Game on the "Clint Westwood" Difficulty