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