Desperados III

After completing the ninth mission you'll unlock your first two Baron's challenges. After that you'll unlock more challenges every time you complete a mission. At the moment of writing, using v.1.4.9.r35847.F, there are 14 challenges.

Most of these challenges are a lot easier and shorter than the story missions and some are just outright silly.

You can choose any challenge you want, but the five easiest challenges are probably:

• One Woman Army
• Hazards of the Trade
• Rescue Aid Society
• Contact!
• Bird Hunting

Some challenges can also be used to easily obtain some trophies:

• Bear Trap Triplets (Good Girl)
• The Devil is in the Details (M-M-M-M-MONSTER KILL)
• Contact! (Another One Bites the Dust & Someone Call the Undertaker)
• For a Few Bullets More (Doubletime)
• Bird Hunting (Damn Good Marksman & Follow Me Darling)

Note: This trophy might be glitched in a good way since it unlocked after completing four challenges for me.