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