Unlockable: How to Unlock:
Baron Bashing Defeat Commander Byron Baron once.
Blastfighter Complete a mission with all parts of the SWAT-12 shotgun equipped.
Cold-Hearted Complete No Negotiation without saving any hostages.
Denied! Defeat a boss before it can escape.
Executioner Defeat over 500 enemies.
Grim Reaper Defeat over 5000 enemies.
Hoarder Collect over 1000 materials.
Is That A Knife? Defeat the Steel Soldier using only your knife.
Kickstarter Contributor You pledged $60 or more on Mercenary Kings and made it happen. Thank you!
Poacher Hunt over 100 animals.
Untouchable Complete a mission in single player without getting hit.
The Hunting Ground area can be reached directly from the upper right side of the home camp. You should have the option to visit that location instead of riding the chopper to a mission location. In the Hunting Ground, you can shoot animals and collect resources that the cook you eventually rescue can turn into temporary stat boosts. You can also find some materials, such as Copper and Amber, and you can discover the hidden Developer Room.
To find that secret room, where you will receive three secret gun pieces with very nice stats, start working through the Hunting Ground until you reach the grassy ledge with a tombstone and flowers. Continue to the right from there, and look for two brown nubs, not far shy of the wall that appears to block you from proceeding any further in that direction. Those nubs are the top of a hidden ladder. Descend along the ladder, then proceed to the right until you reach another wall. You can roll to pass through that wall, then continue advancing to the right (check your map) to progress through some chambers and finally reach the developer room. Talk to each of the various developers to learn what role they played in the game, and to receive equipment from several of them.