Here is the full list of all 42 M.A.R.S. achievements.
Reach Level 100
Achieve MVP 1,000 times
Kill 10,000 players in PVP
Kill 5000 Brute Enemies
Kill 5000 Zombie Brute Enemies
Kill 5000 Zombie Animal Enemies
Kill 5000 Mechanical Enemies
Kill 5000 Zombie Enemies
Kill 5000 Human Enemies
Use 1000 silver bullets
Complete the map Sub-Optimal on the Nightmare difficulty.
Complete the Mercy Killing Map in Kill Every Thing 2.0 Mode on Nightmare Difficulty
Defeated Julia and Boris on the map Liberation '45
Kill 500 Enemys with Grenades
Use 1000 gold bullets
Complete the Mercy Killing Map in Kill Every Thing 2.0 Mode on Normal Difficulty
Kill 200 Players in the PVP
Have your drone reach level 25
In the Head Hunter mode, achieve the largest head that you can hold above your shoulders
Reach Level 50
Reach Level 35
Revive teammates 100 times
Shoot for the first time in the Platinum Shooting Gallery
Complete a mission in nightmare difficulty
Craft an Item.
Complete the map Big Dam Heroes on the Nightmare difficulty
Complete the Mercy Killing Map in Kill Every Thing 2.0 Mode on Hard Difficulty
Receive day 7 roll call rewards
Reach Level 15
In Multiplayer, save a total of 50 teammates from death
Equip a Calling Card
Complete a mission without dying
Complete the Mercy Killing Map in Kill Every Thing 2.0 Mode on Easy Difficulty
Complete any map on the Nightmare difficulty without using any teamwide revives
Kill 100 or more players in PVP Multiplayer
Wear an Cosmetic Item in every Slot.
Reach Level 10
Fail a mission
Equip a drone in your loadout
Reach Level 5
Aquire your first epic rarity weapon
Upgrade a Legacy weapon all the way to Mk.5