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