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.
Lose the first mission
Complete the Tutorial
Open a Gate in Zombie level
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
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
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