Here is the full list of all 14 Mainframe Defenders achievements.
Finish a game with unit having 70+ hull or 15+ armor
Apply 5 different status effects on a single enemy
Complete the final mission
Kill a unit while this unit has 3 times the max heat
Kill a unit with 60+ Corrosion stacks
Complete Matter Raid and pick up 5 caches
Finish the game on Very Hard difficulty
Finish the game without using rare items
Finish the game while having 1000+ matter
Finish the game on Easy difficulty
Finish the game on Normal difficulty
Unlock all units and items
Finish the game without any squad unit deaths
Finish the game on Hard difficulty