Here is the full list of all 51 Strain Tactics achievements.
Have 5 units overwatch at the same time
Have a Strain onboard the helibase
Kill an enemy from a very long range
Complete 10 Missions
Complete any mission with only melee weapons
Endure training by D34F PNCH
Push butt into enemy face enough times until ded
Consult the Info Kiosk, Cpl Diu, and K-41
Kill 5 strain within 1 sec
Kill a unit while moving and force-firing
Arrive on a mission site with Strain and leave immediately
Destroy 2076 strain
Play on slow mo for more than 5 minutes
Lose an entire team of 5 to infection
Have more than 1,000,000 credits
Do not revive any team members until you complete Heartbreaker
Kill 30 Strain without moving an inch
Unlock 20 Items
Unlock 20 Units
Dress up and arm a unit like a Panzer Cop
Destroy an RPG in flight
Kill 10 units while [blinded]
Kill 200 enemies with melee weapons
Kill 200 enemies with pistols
Kill 200 enemies with shotguns
Kill 200 enemies with SMGs
Kill 200 enemies with Rifles
Kill 200 enemies with the Tactical Minigun
Kill 200 enemies with Heavy Battle Rifle
Kill 200 enemies with fire
Kill 200 enemies with explosives
Kill 100 enemies with the 12.5mm
Kill 200 enemies with the 30mm
Kill 100 enemies with the 20mm Monster Killer
Kill 200 enemies with the SAW
Kill 10 enemies with Tactical Throwing Knife
Kill 500 enemies using Force Fire
They can't hurt me now
Consume 6 beers during a mission
Deploy and detonate a Dirty Bomb
Deploy a sandbag 5 times in a mission
Fully level a unit
Sell a unit in a Cryopod
Field a single unit and complete a mission
Complete all Missions
Lose Outpost 826
Do not have the Breachers follow on Heartbreaker
Complete 25 Missions
Complete 50 Missions
Complete 100 Missions
Complete 200 Missions