Here is the full list of all 29 Survivor Mercs achievements.
Survive and defeat the Oilrig boss
Survive and defeat the PhenX boss
Defeat 10 000 enemies over any number of Operations
Defeat 50 000 enemies over any number of Operations
Defeat 100 000 enemies over any number of Operations
Defeat 500 000 enemies over any number of Operations
Defeat 1 000 000 enemies over any number of Operations
Build 2 rooms in your Bunker HQ
Build 3 rooms in your Bunker HQ
Build 4 rooms in your Bunker HQ
Build 5 rooms in your Bunker HQ
Survive an Operation with Critter at or above level 20
Survive an Operation with Curveball at or above level 20
Survive an Operation with Silverback at or above level 20
Survive an Operation with Reaper at or above level 20
Survive an Operation with Shredder at or above level 20
Survive an Operation with Hail at or above level 20
Survive an Operation with Priest at or above level 20
Survive an Operation with Clank at or above level 20
Survive an Operation with Scorch at or above level 20
Survive an Operation with Operator at or above level 20
Survive an Operation with Chemtrail at or above level 20
Survive an Operation with Spark at or above level 20
Survive an Operation with Nubetube at or above level 20
Survive an Operation with Deathstar at or above level 20
Survive an Operation with Hogsheadat or above level 20