Here is the full list of all 11 They Always Run achievements.
Complete the Game
Find Out the Truth About Aiden
Carry All the Criminals in Your Arms
Buy Ammo in the Store 25 Times
Defeat Mueller in the Second Fight
Kill 100 Enemies with Pistols
Get a Reward for 30 Wanted Bandits
Find and Open 50 Chests in the Game
Complete the Bounty Hunter Guild Test
Kill Basim Salamander Instead of Stunning
Hand Over the Rat Alive