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