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