Here is the full list of all 25 Tiny Troopers achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Beat Chapter 3
Kill 50 Enemies with Airstrike
Fully Upgrade Your Squad
Kill 50 Enemies with Rockets
Kill 50 Enemies with Delta Force
Lose 5 Troopers to Mines
Kill 50 Enemies with Grenades
Beat Chapter 2
Destroy 10 Tanks
Kill 50 Enemies with Machine Gunner
Order 10 items from HQ
Destroy 10 Towers
Beat Chapter 1
Use Airstrike to Kill 3 Enemies At Once
Use one of each heavy weapon on a single mission
Earn 200,000 Command Points
Lose the first mission
Collect 10 Medicrates in Zombie level
Revive fallen squad members 10 times in Zombie level
Get a full squad in Zombie level
Kill 100 Zombie chickens
Open a Gate in Zombie level
Collect 25 Dog Tags
Kill 100 Enemies
Complete the Tutorial