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