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