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