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