For this achievement you must complete a mission in single player without firing a single shot. That means you must use Emplacements. You'll need the best Emplacements to make this possible. Once you do, it is recommended that you attempt this on the very first mission in Europe called Beach.
When using tripod legs that have Quickload, press A to activate the leg special. When you need a quicker reload, press [Reload] and immediately press A again. Your ammo should be re-filled as soon as your trench is up and able to move again.
Medals are awarded based on how well you held your ground and performed during the mission (i.e. how well you protected the objective or how quickly you defeated a boss). The highest-ranking Gold Medals are earned if no less than 80% of the primary objective's health remains by the end.
For boss levels, defeat the following within the corresponding estimated time frame:
LEVEL - TIME FRAME Africa - 135 seconds. Europe - 40 seconds. Pacific - 320 seconds.
ACHIEVEMENT - HOW TO UNLOCK Bandolier of Brothers (5 points) - Completed a mission with 4 players. Scrap Snatcher (10 points) - Collected 10,000 Scrap. Battle Buds (20 points) - Completed 10 Missions with 2 or more players. African Allies (5 points) - Defeated the Guardian of the Southern Terminal with 2 or more players. European Entourage (5 points) - Defeated the Northern Pylon with 2 or more players. Pylon Pillager (10 points) - Defeated the Northern Pylon. Mobile Trench Recruit (5 points) - Completed Mobile Trench training. Terminal Terminator (10 points) - Defeated the Guardian of the Southern Terminal. Rainmaker (10 points) - Earned $20,000 from mission completion rewards. Farnsworth Finisher (10 points) - Defeated Vlad. Medal of Honor (30 points) - Earned a Gold Medal on every mission. Silver Star (20 points) - Earned a Silver Medal on every mission. Big Spender (5 points) - Purchased an item in the store. Conscientious Objector (5 points) - Completed a solo mission without firing a shot. Razputin (5 points) - Completed a mission while wearing the uniform of an elite PSI agent. Monovision Massacre (15 points) - Defeated 3500 Monovisions. Pacific Partnership (5 points) - Defeated Vlad with 2 or more players. Trickshooter (5 points) - Killed an enemy with a ricochet sniper shot after 4 bounces. Bronze Star (15 points) - Earned a Bronze Medal on every mission. Pounder (5 points) - Destroyed 5 Enemies with a single explosion.
"Rise Of The Martian Bear" achievements ACHIEVEMENT - HOW TO UNLOCK Bear Buster (25 points) - Defeat the Martian Bear. Swamp Survivor (10 points) - Complete wave 20 on Survival: Swamp. Settlement Savior (15 points) - Complete wave 30 on Survival: Settlement.