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