Here is the full list of all 36 Desperados III achievements.
Complete 5 of the Baron's Challenges.
Make guards follow Kate for 1,000 meters total.
Hide 750 bodies.
Kill 75 guards with Bianca.
Kill 6 guards at once using only a single skill.
Kill 10 small animals in one mission.
Earn 90 badges.
Kill 31 hidden Mimimi devs.
Kill all 3 golden chickens.
Find a patient for the dentist.
Kill 200 guards using Cooper's double shot.
Interrupt an important healing procedure.
Kill DeVitt.
Enjoy some cupcakes during a picnic.
Defeat Frank.
Decide the outcome of a duel.
Knock out your father.
Kill 5 guards at once with dynamite.
Take care of DeVitt.
Jump from a tower into a cart of hay.
Kill 1,000 guards.
Kill 75 Long Coats.
Snipe 50 guards with McCoy.
Mind control 25 guards with Isabelle.
Kill 15 of the hidden Mimimi devs.
Meet Frank on a boat.
Find Wayne.
Hide 250 bodies.
Execute a plan with all five characters.
Return the money to the bank.
Make someone follow your footprints for 25 meters.
Kill 500 guards.
Blow up a bridge.
Kill 50 guards using the environment.
In the first part of the mission, burn 5 guards at once with oil traps.
Finish a mission on "Desperado" difficulty.